U.S. patent application number 15/880330 was filed with the patent office on 2018-05-31 for switchable diplexer with physical layout to provide improved isolation.
The applicant listed for this patent is Entropic Communications, LLC. Invention is credited to Branislav Petrovic, Tarandeep Virk, Younghuang Zeng.
Application Number | 20180152209 15/880330 |
Document ID | / |
Family ID | 50025390 |
Filed Date | 2018-05-31 |
United States Patent
Application |
20180152209 |
Kind Code |
A1 |
Zeng; Younghuang ; et
al. |
May 31, 2018 |
Switchable Diplexer With Physical Layout To Provide Improved
Isolation
Abstract
A switchable diplexer includes a plurality of bandpass filters
having passbands for the frequency bands in which communication
across a communication channel is desired. The bandpass filters can
be arranged in groups of bandpass filters located adjacent to one
another physically. Further, a group of bandpass filters can
include a plurality of bandpass filters having a stop band in a
common frequency range of interest. A plurality of switches can be
provided to switch the desired bandpass filter into the circuit to
allow communication on its corresponding band. The switches can
therefore be electrically coupled to the passband filters and
configured to select one of the plurality of bandpass filters for
signal communication on the communication channel.
Inventors: |
Zeng; Younghuang; (Carlsbad,
CA) ; Petrovic; Branislav; (Carlsbad, CA) ;
Virk; Tarandeep; (Carlsbad, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Entropic Communications, LLC |
Carlsbad |
CA |
US |
|
|
Family ID: |
50025390 |
Appl. No.: |
15/880330 |
Filed: |
January 25, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14788548 |
Jun 30, 2015 |
9882586 |
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15880330 |
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13566470 |
Aug 3, 2012 |
9071388 |
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14788548 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04B 1/006 20130101;
H04L 5/00 20130101; H04B 1/0057 20130101; H04N 7/104 20130101; H04N
21/6118 20130101; H04N 21/4383 20130101 |
International
Class: |
H04B 1/00 20060101
H04B001/00; H04N 7/10 20060101 H04N007/10; H04L 5/00 20060101
H04L005/00 |
Claims
1. A switchable diplexer, comprising: a plurality of bandpass
filters, the bandpass filters having a predetermined passband; and
a plurality of switches coupled to the passband filters; wherein:
the bandpass filters are arranged in groups of bandpass filters, a
first of said groups comprising a first bandpass filter having a
passband in a first frequency range and a second bandpass filter
having a passband in a second frequency range that at least
partially overlaps the first frequency range, the first bandpass
filter and the second bandpass filter being electrically arranged
in parallel relation to one another, and a second of said groups
comprising a third bandpass filter having a passband in a third
frequency range and fourth bandpass filter having a passband in a
fourth frequency range that at least partially overlaps with the
third frequency range, the third bandpass filter and the fourth
bandpass filter being electrically arranged in parallel relation to
one another.
2. The switchable diplexer of claim 2, wherein the plurality of
switches comprise primary and secondary switches, and wherein the
plurality of bandpass filters in a given group of bandpass filters
share common secondary switches.
3. The switchable diplexer of claim 2, wherein none of the
plurality of bandpass filters in a given group share a common
secondary switch with a bandpass filter in another group.
4. The switchable diplexer of claim 2, wherein the groups of
bandpass filters comprise two groups of two bandpass filters each,
and wherein the switches comprise: two primary switches each
connected to a communication link and configured to switch one of
the two groups into the communication link; and a pair of secondary
switches for each group of bandpass filters, each pair of secondary
switches having a first secondary switch coupled to one of the
primary switches and a second secondary switch coupled to another
one of the primary switches, each pair of secondary switches
configured to select one of the two bandpass filters in their
respective group.
5. The switchable diplexer of claim 2, wherein the groups of
bandpass filters comprise M groups of N bandpass filters each, and
wherein the switches comprise: two primary switches each connected
to a communication link and configured to switch one of the M
groups into the communication link; and a pair of secondary
switches for each of the M groups of N bandpass filters, each pair
of secondary switches having a first secondary switch coupled to
one of the primary switches and a second secondary switch coupled
to another one of the primary switches, each pair of secondary
switches configured to select one of the N bandpass filters in
their respective group.
6. The switchable diplexer of claim 5, wherein when the primary
switches are configured to select one of the groups of bandpass
filters, other of the M groups of N bandpass filters are deselected
by the primary switches, and further wherein each pair of secondary
switches for the deselected groups of bandpass filters are set in a
complementary configuration.
7. The switchable diplexer of claim 5, wherein N is the same
quantity for each of the M groups.
8. The switchable diplexer of claim 5, wherein N is different for
one or more of the M groups.
9. The switchable diplexer of claim 1, wherein a first bandpass
filter in at least one of the groups of bandpass filters has a high
rejection frequency range that is at least partially overlapping a
high rejection frequency range of a second bandpass filter in the
at least one the groups of bandpass filters.
10. The switchable diplexer of claim 9, wherein the high rejection
frequency range is a predetermined frequency range of high
rejection.
11. A switchable diplexer, comprising: a first primary switch
comprising a common terminal and M selectable terminals; a first
set of M secondary switches, each secondary switch comprising a
common terminal and N selectable terminals, wherein the common
terminal of each switch in the first set of M secondary switches is
connected to one of the selectable terminals of the first primary
switch; a second primary switch comprising a common terminal and M
selectable terminals; a second set of M secondary switches, each
secondary switch comprising a common terminal and N selectable
terminals, wherein the common terminal of each switch in the second
set of M secondary switches is connected to one of the selectable
terminals of the second primary switch; and a plurality of bandpass
filters arranged in M groups of N bandpass filters, wherein: a
first of said M groups comprising a first bandpass filter having a
passband in a first frequency range and a second bandpass filter
having a passband in a second frequency range that at least
partially overlaps with the first frequency range, the first
bandpass filter and the second bandpass filter being electrically
arranged in parallel relation to one another, a second of said M
groups comprising a third bandpass filter having a passband in a
third frequency range and a fourth bandpass filter having a
passband in a fourth frequency range that at least partially
overlaps with the third frequency range, the third bandpass filter
and the fourth bandpass filter being electrically arranged in
parallel relation to one another, and each bandpass filter having a
first terminal connected to one of the N selectable terminals of
one of the first set of M secondary switches and a second terminal
connected to one of the N selectable terminals of a corresponding
one of the second set of M secondary switches.
12. The switchable diplexer of claim 11, wherein bandpass filters
in a given group of bandpass filters share a common switch of the
first set of M secondary switches and a common switch of the second
set of M secondary switches.
13. The switchable diplexer of claim 11, wherein none of the
plurality of bandpass filters in a given group share a common
secondary switch with a bandpass filter in another group.
14. The switchable diplexer of claim 11, wherein the M groups of N
bandpass filters comprise two groups of two bandpass filters each,
and wherein the switches comprise: the first and second primary
switches each connected to a communication link and configured to
switch one of the two groups into the communication link; and a
pair of the first set and second set of secondary switches for each
group of bandpass filters, each pair of secondary switches having a
first secondary switch coupled to the first primary switch and a
second secondary switch coupled to the second primary switch, each
pair of secondary switches configured to select one of the two
bandpass filters in their respective group.
15. The switchable diplexer of claim 11, wherein when the primary
switches are configured to select one of the M groups of N bandpass
filters, and other of the M groups of N bandpass filters are
deselected by the primary switches, and further wherein each pair
of secondary switches for the deselected groups of bandpass filters
are set in a complementary configuration.
16. The switchable diplexer of claim 11, wherein N is the same
quantity of bandpass filters for each of the M groups.
17. The switchable diplexer of claim 11, wherein N is a different
quantity of bandpass filters for one or more of the M groups.
18. The switchable diplexer of claim 11, wherein the number of N
selectable terminals of a switch pair in the first and second set
of M secondary switches is equal to or greater than the number of
bandpass filters in a group of bandpass filters corresponding to
that switch pair.
19. The switchable diplexer of claim 11, wherein the number of N
selectable terminals of a switch pair in the first and second set
of M secondary switches is greater than a number of bandpass
filters in a group of bandpass filters and at least one of the N
selectable terminals of each secondary switch is connected to a
signal ground.
20. The switchable diplexer of claim 11, wherein the at least one
of the first and second bandpass filters has an identified high
rejection frequency range that is at least partially overlapping an
identified high rejection frequency range of the other of the first
and second bandpass filters in the group.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY
REFERENCE
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/788,548 filed on Jun. 30, 2015, which is a
continuation of U.S. patent application Ser. No. 13/566,470 filed
on Aug. 3, 2012. Each of the above identified applications is
hereby incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] The present invention relates generally to network
communications, and more particularly, some embodiments relate to
physical layouts for a switchable diplexer to provide improved
signal isolation.
DESCRIPTION OF THE RELATED ART
[0003] A local network may include several types of devices
configured to deliver subscriber services throughout a home, office
or other like environment. These subscriber services include
delivering multimedia content, such as streaming audio and video,
to devices located throughout the location. As the number of
available subscriber services has increased and they become more
popular, the number of devices being connected the home network has
also increased. The increase in the number of services and devices
increases the complexity of coordinating communication between the
network nodes. This increase also generally tends to increase the
amount and types of traffic carried on the network.
[0004] The network of FIG. 1 is one example of a multimedia network
implemented in a home. In this example, a wired communications
medium 100 is shown. The wired communications medium might be a
coaxial cable system, a power line system, a fiber optic cable
system, an Ethernet cable system, or other similar communications
medium. Alternatively, the communications medium might be a
wireless transmission system. As one example of a wired
communication medium, with a Multimedia over Coax Alliance (MoCA
.RTM.) network, the communications medium 100 is coaxial cabling
deployed within a residence 101 or other environment. The systems
and methods described herein are often discussed in terms of this
example home network application, however, after reading this
description, one of ordinary skill in the art will understand how
these systems and methods can be implemented in alternative network
applications as well as in environments other than the home.
[0005] The network of FIG. 1 comprises a plurality of network nodes
102, 103, 104, 105, 106 in communication according to a
communications protocol. For example, the communications protocol
might conform to a networking standard, such as the well-known MoCA
standard. Nodes in such a network can be associated with a variety
of devices. For example, in a system deployed in a residence 101, a
node may be a network communications module associated with one of
the computers 109 or 110. Such nodes allow the computers 109, 110
to communicate on the communications medium 100. Alternatively, a
node may be a module associated with a television 111 to allow the
television to receive and display media streamed from one or more
other network nodes. A node might also be associated with a speaker
or other media playing devices that plays music. A node might also
be associated with a module configured to interface with an
internet or cable service provider 112, for example to provide
Internet access, digital video recording capabilities, media
streaming functions, or network management services to the
residence 101. Also, televisions 107, set-top boxes 108 and other
devices may be configured to include sufficient functionality
integrated therein to communicate directly with the network.
[0006] With the many continued advancements in communications
technology, more and more devices are being introduced in both the
consumer and commercial sectors with advanced communications
capabilities. The introduction of more devices onto a communication
network can task the available bandwidth of communication channels
in the network. For examples, service providers such as satellite
TV providers include MoCA enabled set-top boxes (STBs) and digital
video recorders (DVRs) with their systems. By using a high-speed
MoCA network to connect DVRs, STBs and broadband access points, the
satellite TV providers offer multi-room DVR from a single box and
allow access to the Internet to provide streaming video on
demand.
[0007] To accommodate additional devices the network bandwidth can
be divided into different frequency bands to allow some level of
simultaneous communication with reduced interference. For example,
to operate on existing coaxial runs in the home, MoCA is capable of
operating at different frequency bands to avoid existing cable TV
signals. For example, in a home with cable TV signals below 1 GHz,
MoCA operates above 1125 MHz in a band called D band. In a home
with satellite L-band signals above 950 MHz MoCA operates between
475 and 675 MHz in a band called E band. To further reduce
interference to existing services, MoCA also features transmit
power control (TPC). TPC reduces the MoCA transmit power by up to
30 dB. Reducing transmit power lowers the likelihood that the MoCA
signal will cause interference to devices operating in other bands.
To further take advantage of the bandwidth provided by the coaxial
cabling, channel stacking switch (CSS) technology is often used to
re-allocate IF video to another portion of the coaxial cable to
provide separate channels for a MoCA home network.
[0008] To accommodate multiple devices on a given communication
channel, a diplexer can be used. For example, a conventional
diplexer includes two or more bandpass filters to allow multiple
signals in different frequency bands to share the same
communication link and to filter out the unwanted signals before
providing the signal to a given device. Such diplexers can provide
a frequency division duplexing (FDD) solution.
[0009] Additionally, switchable diplexers can be used to allow
selective access to the physical layer by different signals in
different frequency bands. This is useful in applications where it
is desirable to allow multiple devices operating at different
frequency bands to share the same coaxial cable network. FIG. 2 is
a diagram illustrating an example of a conventional switchable
diplexer. Referring now to FIG. 2, this conventional diplexer 200
includes four bandpass filters and six switches to select one of
the four bandpass filters for communication. Particularly, this
example includes a D-Band bandpass filter 204, an F-Band bandpass
filter 206, a D-Low-Band bandpass filter 208, and an E-Band
bandpass filter 210. D-Band bandpass filter 204 is configured to
pass signals in the 1,125 MHz to 1,675 MHz passband range, and to
reject signals outside that passband range. Likewise, the F-Band
bandpass filter 206 has a passband of 650 MHz-875 MHz with high
rejection requirements in the 1300-2150 MHz range, the D-Low-Band
bandpass filter 208 has a passband of 1,125 MHz to 1,225 MHz, and
the E-Band bandpass filter 210 has a passband of 475 MHz to 675 MHz
and high rejection specification from 950 MHz to 2,150 MHz.
[0010] Switches, SW1-SW6 are provided to switch the selected
bandpass filter into the signal path. In the illustrated example,
three switches SW1, SW2 and SW5 are provided at a first side to
switch the signal to/from the desired one of the plurality of
bandpass filters 204-210. When configured as shown, switches SW1,
SW2 and SW5 are configured to switch the signal to/from E-Band
bandpass filter 210. Likewise, at the other side, three switches
SW3, SW4 and SW6 are provided to switch the signal to/from the
selected bandpass filter onto the signal path. When configured as
shown, switches SW3, SW4 and SW6 are configured to switch the
output signal to/from E-Band bandpass filter 210 from/onto the
communication channel. As used in this document, top-level switches
such as switches SW1 and SW4 are referred to as primary switches,
while the next level switches SW2, SW3, SW5 and SW 6 are referred
to as secondary switches.
BRIEF SUMMARY OF EMBODIMENTS OF THE INVENTION
[0011] According to embodiments of the systems and methods
described herein, various configurations for switchable bandpass
filter and diplexer combinations are provided. In accordance with
some embodiments of the systems and methods described herein, a
plurality of diplexers and bandpass filters are provided with
switches to allow selection of different communication bands for
communication over a communication channel. Particularly, in some
embodiments, switchable bandpass filter and diplexer combinations
are provided to allow communication of network and cable TV signals
over a coaxial cable installation. More particularly, in some
embodiments, switchable bandpass filter and diplexer combinations
are provided to allow communication of MoCA network communications
and cable TV signals over a coaxial cable installation.
[0012] In some embodiments, a switchable filter and diplexer
circuit, includes a plurality of diplexers, each diplexer having a
plurality of one or more passbands. For example, in some
embodiments, a given diplexer includes a passband for network
communications (such as, for example, MoCA network communications)
and a passband for cable TV transmission. The switchable filter and
diplexer circuit in these embodiments also includes a plurality of
bandpass filters having a predetermined passband and stopband.
Preferably, at least some of the bandpass filters have a passband
different from the passband of the other of the plurality of
bandpass filters.
[0013] A plurality of switches may be provided and coupled to the
diplexers and to the passband filters. The switches may be
configured to select one of the plurality of bandpass filters or
diplexers for signal communication on a communication channel.
[0014] In some embodiments, the bandpass filters are arranged in
groups of bandpass filters located adjacent to one another
physically, and a group of bandpass filters includes a plurality of
bandpass filters having a stop band in a common frequency range of
interest.
[0015] A variety of different switching arrangements can be
provided to allow selection and communication of network and
television signals. In one embodiment, the plurality of switches
comprise a first pair of switches coupled to the plurality of
bandpass filters and diplexers and configured to select one of the
bandpass filters and diplexers for network communication, and a
third switch having input terminals coupled to the diplexers and
configured to select one of the diplexers for TV signal
communication. In some embodiments, the third switch is coupled to
at least one of the switches of the first pair of switches such
that when a given diplexer is selected by the at least one of the
switches of the first pair of switches that same diplexer is
selected by the third switch.
[0016] In various embodiments, the diplexers include a cable TV
bandpass filter. The cable TV bandpass filter can include a
low-pass filter configured to have a passband of less than or equal
to 1002 MHz. In other embodiments, the cable TV bandpass filter can
include a low-pass filter configured to have a passband for other
TV signals such as, for example, a passband of less than or equal
to 864 MHz.
[0017] In some embodiments, a switchable filter and diplexer
circuit includes a first switch having a common terminal and a
plurality of selectable terminals; a second switch having a common
terminal and a plurality of selectable terminals; a third switch
having a common terminal and a plurality of selectable terminals; a
plurality of diplexers, each diplexer having a plurality of
passbands and each diplexer having a first terminal connected to
one of the plurality of selectable terminals of the first switch, a
second terminal connected to one of the plurality of selectable
terminals of the third switch, and a third terminal connected to
one of the plurality of selectable terminals of the second switch;
and a plurality of bandpass filters, the bandpass filters having a
predetermined passband, wherein at least some of the bandpass
filters have a passband different from the passband of the other of
the plurality of bandpass filters, each of the bandpass filters
having a first terminal connected to one of the plurality of
selectable terminals of the first switch, a second terminal
connected to one of the plurality of selectable terminals of the
third switch.
[0018] In some embodiments, the bandpass filters include an E-band
bandpass filter, an F-band bandpass filter and an H-band bandpass
filter electrically arranged in parallel relation to one another
and the diplexers comprises a first diplexer with a D-band bandpass
filter, a second diplexer with a D-low band bandpass filter, and a
third diplexer with a D-high band bandpass filter electrically
arranged in parallel relation to one another. The diplexers can
further include a cable TV bandpass filter having, for example, a
low-pass filter configured to have a passband of less than or equal
to 1002 MHz.
[0019] The bandpass filters may be arranged in groups of bandpass
filters located adjacent to one another physically, wherein a group
of bandpass filters comprises a plurality of bandpass filters
having a stop band in a common frequency range of interest. The
bandpass filters can include a plurality of bandpass filters each
having an identified rejection frequency range that is at least
partially overlapping an identified frequency rejection range of
the other bandpass filters in the group. The identified rejection
frequency range can be a predetermined frequency range of high
rejection.
[0020] The bandpass filters and diplexers may be grouped into M
groups of N bandpass filters or diplexers each, wherein the first
and third switches include a first and third switch pair for each
group of bandpass filters or diplexers. The system can further
include a first primary switch having a common terminal and at
least M selectable terminals, and a second primary switch having a
common terminal at least M selectable terminals, wherein
corresponding ones of the selectable terminals of the first and
second primary switches are connected to the common terminals of
the first and third switches for a given group of bandpass filters
or diplexers. In some embodiments, N is the same quantity of
bandpass filters or diplexers for each of the M groups. In other
embodiments, N is a different quantity of bandpass filters or
diplexers for one or more of the M groups.
[0021] Because it is often desirable to share the channel among
components operating at different frequencies, at least some of the
bandpass filters have a passband different from the passband of the
other of the plurality of bandpass filters. A plurality of switches
can be provided to switch the desired bandpass filter into the
circuit to allow communication on its corresponding band. The
switches can therefore be electrically coupled to the passband
filters and configured to select one of the plurality of bandpass
filters for signal communication on the communication channel. In
various embodiments, the bandpass filters are arranged in groups of
bandpass filters located adjacent to one another physically.
Further, a group of bandpass filters comprises a plurality of
bandpass filters having a stop band in a common frequency range of
interest.
[0022] In some configurations multi throw switches can be used to
switch a bandpass filter with a desired into and out of the circuit
with one level of switches. In other configurations, the switches
are provided as primary-level switches and secondary switches. The
primary switches can be used to select groups of bandpass filters
into and out of the circuit; the secondary switches can be used to
select a given bandpass filter within the group. Accordingly, in
some embodiments, the plurality of bandpass filters in a given
group of bandpass filters share common secondary switches. In
further embodiments, additional levels of switching can be provided
such as, for example, to accommodate subgroups of bandpass filters.
To provide additional isolation, some embodiments can be provided
in which none of the plurality of bandpass filters in a given group
share a common secondary switch with a bandpass filter in another
group.
[0023] In one example embodiment, the groups of bandpass filters
include at least two groups of at least two bandpass filters each,
and the switches include primary switches and secondary switches.
In a further example, the switchable diplexer includes two primary
switches each connected to a communication link and configured to
switch one of the two groups into the communication link; and a
pair of secondary switches for each group of bandpass filters, each
pair of secondary switches having a first secondary switch coupled
to one of the primary switches and a second secondary switch
coupled to the other of the primary switches, each pair of
secondary switches configured to select one of the two bandpass
filters in their respective group.
[0024] The switchable diplexer in various embodiments is scalable
depending on system requirements and the groups of bandpass filters
can include M groups of N bandpass filters each (where M, N are
integer numbers). The number of bandpass filters N in each of the M
groups can be the same across all groups or it can vary for one or
more of the groups. In other words, in some embodiments N is the
same quantity for each of the M groups of bandpass filters, while
in other embodiments, N is different for one or more of the M
groups. In embodiments with primary and secondary switches, there
can be two primary switches each connected to a communication link
and configured to switch one of the M groups into the communication
link. There can also be included a pair of secondary switches for
each of the M group of bandpass filters, each pair of secondary
switches having a first secondary switch coupled to one of the
primary switches and a second secondary switch coupled to the other
of the primary switches, each pair of secondary switches configured
to select one of the N bandpass filters in their respective
group.
[0025] In embodiments with primary and secondary switches are used,
in some embodiments when the primary switches are configured to
select one of the groups of bandpass filters, the other of the M
groups of bandpass filters are deselected by the primary switches,
and further wherein each pair of secondary switches for the
deselected groups of bandpass filters are set in a complementary
configuration.
[0026] In various embodiments, bandpass filters can be cascaded
with a diplexer to create a cascaded diplexer leg with selectable
passbands. This can, in some embodiments, simplify the design and
alleviate the need for switching to select TV bands at the diplexer
output while still allowing multi-band network support.
[0027] In one embodiment, a cascaded diplexer circuit, includes a
diplexer comprising a plurality of first bandpass filters each
having a passband; and a second bandpass filter having a passband
and two terminals, and coupled in series with a determined one of
the first bandpass filters of the diplexer; and first and second
switches coupled in series with the second bandpass filter and the
determined one of the first bandpass filters of the diplexer, and
configured to selectably switch the second bandpass filter into the
circuit. Preferably, the passband of the second bandpass filter is
chosen to limit the passband of the determined one of the first
bandpass filters, such that when the second bandpass filter is
switched into the circuit, the passband of the diplexer leg is
reduced. In some embodiments, the passband of the second bandpass
filter is a subset of, or overlaps with, the passband of the
determined one of the first bandpass filters.
[0028] The cascaded diplexer circuit can be further configured to
include a plurality of additional bandpass filters connected in
parallel with the diplexer and second bandpass filter, the
additional bandpass filters having a predetermined passband; and
second and third switches coupled to the additional passband
filters and to the diplexer and second bandpass filter circuit leg,
the second and third switches configured to select one of the
plurality of additional bandpass filters or the diplexer and second
bandpass filter circuit leg for signal communication on a
communication channel.
[0029] A shunt can be included and coupled between the first and
second switches and arranged in parallel circuit relation to the
second bandpass filter to allow the second bandpass filter to be
effectively removed from the circuit. Also, a third bandpass filter
can be included and coupled between the first and second switches
and in parallel circuit relation to the second bandpass filter.
Additional bandpass filters can also be provided. The first and
second switches can be configured to selectably connect the second
bandpass filter, the third bandpass filter or the shunt into the
circuit. In some embodiments, the first and second switches are
configured to selectably connect the second bandpass filter or the
third bypass filter into the circuit.
[0030] In other embodiments, a cascaded diplexer circuit includes:
diplexer comprising a common terminal and first and second
band-specific terminals, and further comprising a first bandpass
filter coupled between the common terminal and the first
band-specific terminal and a second bandpass filter coupled between
the common terminal and the second band-specific terminal, the
bandpass filters having a passband and a stop band; a third
bandpass filter having first and second terminals, wherein the
first terminal of the third bandpass filter is coupled to the first
band-specific terminal of the diplexer; and a first switch having a
common terminal coupled to the first band-specific terminal of the
diplexer and a first selectable terminal coupled to a first
terminal of the third bandpass filter, wherein the switch is
configured to selectably switch the third bandpass filter into and
out of the diplexer circuit. Preferably, in some embodiments, the
passband of the third bandpass filter limits the passband of the
first bandpass filter. Accordingly, the passband of the third
bandpass filter can be a subset of, or overlap with, the passband
of the first bandpass filter.
[0031] The cascaded diplexer circuit can further include a
plurality of additional bandpass filters connected in parallel with
the diplexer and third bandpass filter, the additional bandpass
filters having a predetermined passband; and second and third
switches coupled to the additional passband filters and to the
diplexer and third bandpass filter circuit leg, the second and
third switches configured to select one of the plurality of
additional bandpass filters or the diplexer and third bandpass
filter circuit leg for signal communication on a communication
channel.
[0032] The cascaded diplexer circuit can also include a second
switch having a first selectable terminal coupled to a second
terminal of the third bandpass filter, and a shunt arranged in
parallel circuit relation to the third bandpass filter and coupling
between a second selectable terminal of the first switch and a
second selectable terminal of the second switch. A fourth bandpass
filter coupled between the first and second switches can also be
included and arranged in parallel circuit relation to the third
bandpass filter. In some embodiments, the first and second switches
are configured to selectably connect the third bandpass filter, the
fourth bandpass filter or the shunt into the circuit.
[0033] The cascaded diplexer circuit can also include a fourth (or
more) bandpass filter coupled between the first and second switches
and in parallel circuit relation to the third bandpass filter. In
such embodiments, the first and second switches can be configured
to selectably connect the fourth bandpass filter or the third
bypass filter into the circuit. The additional bandpass filters can
include at least one of an E-band bandpass filter, an F-band
bandpass filter and an H-band bandpass filter electrically arranged
in parallel relation to one another.
[0034] Other features and aspects of the invention will become
apparent from the following detailed description, taken in
conjunction with the accompanying drawings, which illustrate, by
way of example, the features in accordance with embodiments of the
invention. The summary is not intended to limit the scope of the
invention, which is defined solely by the claims attached
hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] The present invention, in accordance with one or more
various embodiments, is described in detail with reference to the
accompanying figures. The drawings are provided for purposes of
illustration only and merely depict typical or example embodiments
of the invention. These drawings are provided to facilitate the
reader's understanding of the systems and methods described herein
and shall not be considered limiting of the breadth, scope, or
applicability of the claimed invention.
[0036] FIG. 1 is a diagram illustrating one example of a home
network environment with which the systems and methods described
herein can be implemented.
[0037] FIG. 2 is a diagram illustrating one example of a
conventional switchable diplexer.
[0038] FIG. 3 is a diagram illustrating an example of a switchable
diplexer in accordance with one embodiment of the systems and
methods described herein.
[0039] FIG. 4 is a diagram illustrating an example of a switchable
diplexer in accordance with another embodiment of the systems and
methods described herein.
[0040] FIG. 5 is a diagram illustrating an example of a combination
switchable diplexer in accordance with one embodiment of the
systems and methods described herein.
[0041] FIG. 6 is a diagram illustrating another example of a
combination switchable diplexer in accordance with one embodiment
of the systems and methods described herein.
[0042] FIG. 7 is a diagram illustrating an example of a cascaded
switchable diplexer in accordance with one embodiment of the
systems and methods described herein.
[0043] FIG. 8 is a diagram illustrating another example of a
cascaded switchable diplexer in accordance with one embodiment of
the systems and methods described herein.
[0044] The figures are not intended to be exhaustive or to limit
the invention to the precise form disclosed. It should be
understood that the invention can be practiced with modification
and alteration, and that the invention be limited only by the
claims and the equivalents thereof.
DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
[0045] Systems and methods described herein include a switchable
diplexer configured in some embodiments to provide a low insertion
loss relative to conventional solutions. Because of crosstalk
between diplexer elements used in switchable diplexers, the
switching components of switchable diplexers are often specified to
have a high enough degree of isolation to reduce or minimize the
adverse effects of signals bleeding through onto an adjacent
diplexer channel. Configuration of the switchable diplexer to
provide placement of components such that bandpass filters having
like passbands are placed adjacent one another helps to reduce the
effects of unwanted crosstalk interference between the bandpass
filter elements.
[0046] The diplexers according to the systems and methods describe
herein include a plurality of bandpass filters that are used to
allow signals of certain frequencies to pass while rejecting, or
filtering out, signals in other frequency bands. The bandpass
filters pass signals within a certain band of frequencies of a
desired bandwidth. This is known as the pass band of the bandpass
filter. The bandwidth is typically defined as the frequency range
between two cut-off points. The frequency cutoff points are
typically 3 dB below the maximum center or resonant peak, although
other parameters can be used to specify the operable passband of
the bandpass filter. Frequency ranges outside the passband are
often referred to as the stop band of the bandpass filter. With
some filters there may be a transition region between the passband
and the stop band. In most applications, the bandpass filter is
used to allow frequencies within the passband to be passed through
the filter while rejecting, or filtering out, unwanted frequencies
outside the passband.
[0047] In addition to specifying a passband, bandpass filters may
specify a level of rejection (typically in dB) for the stop band.
Also, one or more frequency ranges of high rejection may be
specified to filter out signals in a frequency range of particular
interest. The level of rejection specified as being a high level of
rejection for the filter depends on the system application and the
signals anticipated on the communication channel. For example, it
may be known in a given application that signals in a certain
frequency range may be present and that such signals, if allowed to
pass, would cause interference on the channel with desired signals
in the passband. As such, the system designer would specify a
sufficient level of rejection in that band (or across a wider band)
to reduce the interference to a desired level to allow system
performance to meet specifications. For example, in some
applications such as in MoCA, the specification for high rejection
in the 1300-2150 MHz range for F-Band bandpass filter 206 can be 65
dB, while the specification for high rejection in the 950-2150 MHz
range for E-band bandpass filter 210 can be 60 dB. As one of
ordinary skill in the art will understand, other levels of
isolation can be specified for a frequency range of high rejection.
Note that in some applications, the entire stop band may be
specified as requiring a high level of rejection.
[0048] Conventional designs such as that shown in FIG. 2 alternate
the placement of bandpass filters so that filters having different
passbands are placed adjacent to one another physically. This is
done with conventional switchable diplexers to reduce coupling or
crosstalk for better isolation. Accordingly, in the example of FIG.
2, the physical layout of bandpass filters 204-210 would be similar
to the layout shown in the schematic diagram, in which D-Band
bandpass filter 204 and D-Low band bandpass filter 208 are
physically separated from each other to avoid cross talk between
signals within the overlapping frequency range of their respective
passbands.
[0049] However, as a result, bandpass filters with different and
non-overlapping passbands are typically placed adjacent one
another. Due to crosstalk between adjacent bandpass filters,
signals filtered out or rejected by the selected bandpass filter
may be coupled into an adjacent bandpass filter and pass through
the output switch and onto the signal path. This phenomenon can be
illustrated with the example configuration shown in FIG. 2. With
continued reference to FIG. 2, consider the case as illustrated in
which a broadband signal is input into switchable diplexer 200 at
switch SW1, is routed to switch SW5, which in turn, routes the
signal to E-Band bandpass filter 210. E-Band bandpass filter 210
passes the portion of the signal from 475 MHz to 675 MHz to switch
SW6. E-Band bandpass filter 210 blocks portions of the signal
outside its passband frequency band in accordance with the filter
characteristics. For example, in one application, E-Band bandpass
filter 210 blocks signals in the 950 MHz-2150 MHz by 60 dB or
greater.
[0050] However, because of the proximity of D-Low Band bandpass
filter 208 to E-Band bandpass filter 210 and the crosstalk between
them, unwanted signals can couple into D-Low Band bandpass filter
208. Particularly, portions of the signal in the stop band of
E-Band bandpass filter 210 that are in the passband of D-Low Band
bandpass filter 208 can couple onto and be passed by D-Low Band
bandpass filter 208. This can be particularly problematic in the
instant example where frequency range specified as the
high-rejection range of E-band bandpass filter 210 overlaps to a
large extent with the pass band of D-low band bandpass filter 208.
Accordingly, signals in this area of specified high rejection can
couple into and be passed by D-low band bandpass filter 208,
degrading the effective rejection in that band.
[0051] To avoid having this crosstalk signal appear at the output
of the switchable diplexer 200, system designers typically specify
output switches with a high enough level of isolation to avoid this
unwanted signal from coupling across the terminals of the switch
and onto the output signal lines. Continuing with this particular
example, E-band bandpass filter 210 requires high rejection in the
950 MHz-2150 MHz range (for example, 60 dB), which overlaps with
the passband of the D-Low Band bandpass filter 208 (1,125 MHz-1,225
MHz). Therefore, the combined isolation ISOS+ISO6 of switches SW5
and SW6 needs to be large enough to sufficiently isolate D-low band
bandpass filter 208. Consider an example where the high rejection
is specified as being 60 dB. In this example, because of coupling
from E-band bandpass filter 210 to D-low band bandpass filter 208,
the combined switch isolation for switches SW5 and SW6 needs to be
on the order of approximately 70 dB (60 dB+10 dB margin) in order
to preserve the integrity of E-Band bandpass filter 210.
[0052] Accordingly, SW5 and SW6 would be typically specified with
sufficient isolation ISO6 between terminals A and B such that
unwanted signals will not couple between terminal B and terminal A.
Likewise, the other switches SW1SW5 are also specified with
sufficient isolation to avoid similar coupling of unwanted signals.
For example, F-band bandpass filter 204 requires high rejection
(for example, 65 dB) in the 1,300 MHz-2,150 MHz range, which covers
the passband of the D-band bandpass filter (1,125 MHz-1,225 MHz).
Therefore the combined isolations of SW2 and SW3 (ISO2 and ISO3)
needs to be in the 75 dB range (65+10) in order to preserve the
integrity of F-band bandpass filter 204. Switches with these levels
of isolation are costly and can drive up the cost of the switchable
diplexer 200.
[0053] One solution to reduce or eliminate unwanted filter
crosstalk would be to provide a large enough degree of physical
separation between the bandpass filters to reduce or eliminate the
crosstalk between them. However, packaging constraints typically
require that the bandpass filters be placed in close enough
proximity to one another such that crosstalk needs to be addressed.
Therefore, according to one embodiment of the systems and methods
described herein, the bandpass filters are arranged
counter-intuitive to conventional wisdom. Particularly, in some
embodiments, the bandpass filters are arranged such that filters
with like passbands are placed adjacent to one another, and filters
with differing passbands are preferably separated from one another.
In other embodiments, the bandpass filters are arranged such that a
filter with a specified high rejection in a given frequency range
is placed adjacent a bandpass filter for which that same frequency
range is in its stop band. In yet other embodiments, the bandpass
filters are arranged such that bandpass filters with like stop
bands are placed adjacent to one another.
[0054] In some embodiments, the placement is made to the extent
practical considering packaging, layout, and other constraints that
may exist for the switchable diplexer. For example, in some
applications, packaging, layout or other constraints may require
that one or more bandpass filters be placed adjacent to one or more
other bandpass filters having differing passbands.
[0055] In some embodiments, two bandpass filters are considered to
have differing passbands where the passbands of the two bandpass
filters are completely non-overlapping. In other embodiments, two
bandpass filters are considered to have differing passbands where
the passbands of the two bandpass filters are only partially
non-overlapping. In some embodiments, two bandpass filters are
considered to have like passbands where the passband of one filter
is the same or substantially the same as the passband of the other
filter. In other embodiments, two bandpass filters are considered
to have like passbands where the passband of one filter overlaps
some or all of the passband of the other filter, or where the
passband of one filter is a subset of the passband of the other
filter. Accordingly, overlap of frequency bands can include the
partial or complete overlap by one band of one filter with a
frequency band of another filter.
[0056] In some embodiments, the amount of overlap for a band of one
filter to be considered like a band of another filter is determined
by a percentage of overlap by one band of the other. For example,
50%, 60%, 70%, 80%, 90% or greater overlap may be considered
sufficient overlap of frequency bands for two filters to be deemed
to have like passbands or stop bands.
[0057] In many embodiments, the passbands and stop bands of the
filters, as well as bands of high rejection, are defined by the
network parameters. Accordingly, a certain percentage of overlap
may not be attainable for each adjacent filter, but adjacencies
instead determined based on optimizing the layout given the
passband and stopband ranges provided. Filter layout and
adjacencies can be determined by choosing the arrangement that
minimizes stop-band crosstalk among the filters. In further
embodiments, Filter layout and adjacencies can be determined by
choosing the arrangement that minimizes stop-band crosstalk for
high rejection bands.
[0058] FIG. 3 is a diagram illustrating an example bandpass filter
layout of a switchable diplexer in accordance with one embodiment
of the systems and methods described herein. In the example
illustrated in FIG. 3, the bandpass filters are arranged such that
filters with like stopbands are placed adjacent to one another, and
filters with differing stopbands are separated from one another.
Referring now to FIG. 3, the illustrated switchable diplexer 300
includes bandpass filters 302-308 and switches SW11-SW16. Like the
example shown in FIG. 2, E, F and D bands are accommodated and
switches SW11-SW16 are provided to switch the selected bandpass
filter into the signal path. In the illustrated example, three
switches SW11, SW12 and SW15 are provided at one side to switch the
signal into/from the desired one of the plurality of bandpass
filters 304-310. When configured as shown, primary switch SW11 and
secondary switches SW12 and SW15 are configured to switch the
signal into/from E-Band bandpass filter 308. Likewise, at the other
side, three switches, primary switch SW13 and secondary switches
SW14, SW16, are provided to switch the signal to/from the selected
bandpass filter from/to the signal path. When configured as shown,
switches SW13, SW14 and SW16 are configured to switch the signal
from E-Band bandpass filter 308 to/from the communication
channel.
[0059] As illustrated in the example of FIG. 3, bandpass filters
are arranged in groups such that bandpass filters with like stop
bands (or with like passbands) are positioned adjacent one another
rather than in an alternating configuration. Therefore, signals
outside the passband of the selected filter are either completely
outside the passband of the adjacent filter or only partially
overlapping the passband of the adjacent filter.
[0060] With continued reference to FIG. 3, in this example E-band
bandpass filter 308 is positioned adjacent F-Band bandpass filter
304, and D-Band bandpass filter 302 is positioned adjacent D-low
band bandpass filter 306. The passband of E-band bandpass filter
308 (475 MHz-675 MHz) is entirely contained with the passband of
F-band bandpass filter 304 (650 MHz-875 MHz) and therefore, only a
portion of those rejected signals outside of the passband of E-band
bandpass filter 308 are within the passband of F-band bandpass
filter 304. Moreover, none of the signals rejected by the passband
of F-band bandpass filter 304 are within the passband of E-band
bandpass filter 308. More importantly in this example, the
frequency range for which high rejections are specified for E-band
bandpass filter 308 (950 MHz-2150 MHz) is completely outside the
passband (i.e. it falls in the stopband) of F-Band bandpass filter
304. Likewise, the frequency range for which high rejections are
specified for F-band bandpass filter 304 (650 MHz-875 MHz) is
completely outside the passband of E-band bandpass filter 308.
Therefore, even if signals in the stop band of E-band bandpass
filter 308 were to couple into the signal path of F-band bandpass
filter 304, those signals would be rejected by the stop band of
F-band bandpass filter 304.
[0061] More particularly, consider an example of a broadband signal
input to switch SW12. If the portion of that signal in the stop
band of E-band bandpass filter 308 were to couple through switch
SW12 to F-band bandpass filter 304, that signal would be rejected
by the stop band of F-band bandpass filter 304. Likewise, if
through crosstalk the signal were to couple from of E-band bandpass
filter 308 to F-band bandpass filter 304, that signal would be
rejected by the stop band of F-band bandpass filter 304.
[0062] As illustrated in the example of FIG. 3, the high rejection
area of E-band bandpass filter 308 is not a part of the passband of
F-Band bandpass filter 304, and vice versa. Therefore the Isolation
requirements (ISO2+ISO3) of the Switches are reduced over the
conventional solution illustrated in FIG. 2. In some embodiments,
for example, the isolation requirements ISO2+ISO3 can be reduced to
the 30 dB range. In other applications, the isolation requirements
ISO2+ISO3 can be reduced to other levels depending on the bandpass
filters used, and system requirements.
[0063] Accordingly, switchable diplexer 300 can be implemented to
reduce the effects of parasitic coupling and to improve isolation
by the physical placement and arrangement of the bandpass filters.
For example, where the diplexer has a first bandpass filter having
a high rejection requirement and second bandpass filter that has a
passband covering the first filter's high rejection band, these
bandpass filters are arranged such that they are not physically
close to each other. For example, they are arranged as remotely
from one another as layout, packaging and overall package size
constraints allow. In the illustrated example, to accomplish this
the filters are grouped according to similarities of passbands or
stop bands.
[0064] Arranging the bandpass filters in groups to position the
bandpass filters adjacent other bandpass filters with like
passbands or like stop bands can improve signal isolation as
described further below. In one embodiment, the bandpass filters
can be arranged in M groups, and each group can comprise N bandpass
filters. In the example depicted in FIGS. 3, M=2 and N=2; that is,
the bandpass filters are arranged in 2 groups and each group
includes 2 bandpass filters. In some embodiments, the number of
bandpass filters N in each group is the same across all groups. In
other embodiments, the number of filters N in each group can vary
from group to group (i.e., N can be different for one or more
groups). Spacing between bandpass filters in the switchable
diplexer can vary or it can be constant. For example, in one
embodiment filter spacing can be constant across the entire
switchable diplexer. In another embodiment, spacing between filters
can vary. In yet another embodiment, spacing between filters of
adjacent groups can be greater than or less than spacing of filters
within a group. It is noted that description herein of arrangement
in terms of groups refers to adjacency of filters and does not
require particular spacing of filters within a group or between
different groups.
[0065] In some embodiments, where the packaging or sizing
constraints permit, spacing between bandpass filters 306 and 304
can be increased to minimize crosstalk between them. Also, in some
embodiments, spacing between bandpass filters 302 and 306 and
between bandpass filters 304 and 308 can be decreased over
conventional solutions.
[0066] Another benefit of the example illustrated in FIG. 3 is that
provided by increased switch isolation. In the example of FIG. 2,
in E-Band operation, unwanted signals coupled into D-band bandpass
filter 204 are isolated from the output by two switches SW5 and
SW6. Likewise, in other bands of operation, isolation is similarly
provided by two switches.
[0067] In the example of FIG. 3, the isolation provided by the
switches can be increased. By arranging SW15 and SW16 into
opposite, or complementary, positions (as illustrated) when the
signal is passing thru SW12 & SW13, (i.e., in E- or F-band
operation), isolation is maintained by 3 switches (ISOI+SO4+SO5)
(or ISO1+ISO6+SO5) instead of 2 switches in the conventional
design. Therefore isolation performance is improved over the
conventional design or lower isolation switches can be used to
achieve the same levels of unwanted signal isolation. Table 1 is a
table illustrating an example configuration of switches for
switchable diplexer 300 using the complementary positioning of
secondary switches SW12, SW13, SW15 and SW16. Note, in
implementations where there are more than 2 bandpass filters in a
given group, the complementary position for the secondary switches
comprises switch positions in which none of the bandpass filters in
the group is selected by the switches at both ends.
TABLE-US-00001 TABLE 1 SW11 SW14 SW12 SW13 SW15 SW16 A A A A A B A
A A A B A A A B B A B A A B B B A B B A A A B B B A A B A B B B B A
B B B B B B A
[0068] Note, also that even though the passband of D-low band
bandpass filter 306 over laps with the high rejection region of
F-band bandpass filter 304 the effects of any crosstalk between
them is isolated by the isolation ISO 11 provided by switch SW11 on
the first end and by switches SW16 and SW14 at the other end (ISO14
and ISO16). In other words, F-band bandpass filter 304 and D-band
bandpass filter 306 use separate secondary switches. This can be
contrasted to the conventional solution in which the bandpass
filters with the high rejection requirements (206 and 210) are
paired with a bandpass filter having a passband overlapping that
region (filters 204 and 208, respectively). In the example of FIG.
2, each pair shares the same terminal of the primary switches SW1
and SW4, and no isolation between them is provided by these primary
switches. Also, each pair shares the same secondary switches--i.e.,
secondary switches SW12 and SW13 for filter pair 204, 206, and
secondary switches SW15 and SW16 for filter pair 208, 210. In other
words bandpass filters 204 and 206 are on the same switch branch
and no isolation from crosstalk between them is provided by primary
switches SW11 or SW 14. The same is true for bandpass filters 208
and 210.
[0069] Although the example illustrated in FIG. 3 uses multiple
SPDT (single pole double throw) switches, other embodiments with
different switching arrangements can be used. For example the three
input switches SW1 1, SW12, SW15 can be replaced by a single SP4T
switch (not shown) to provide selectable switching of the signal to
one of the four bandpass filters 302, 304, 306, 308. Likewise, an
SP4T switch can replace the three SPDT switches SW13, SW14, SW16 at
the output. As would be apparent to one of skill after reading this
description, other switch configurations can be used for diplexers
having a different number of bandpass filters. For example, an SPXT
switch can be used to select from among X bandpass filters in a
switchable diplexer, where X represents the number of bandpass
filters.
[0070] Multi-throw switches typically exhibit different isolations
between different terminal pairs for a given frequency range. In
various embodiments, the contacts of the multi-throw switch
assigned to each bandpass filter can be selected based on the
relative isolations between pairs of those contacts.
[0071] In yet another embodiment, the switches can be configured to
include an additional position to improve isolation. In operation,
for an unused branch of the diplexer circuit, the switches can be
placed in the unused position to increase isolation. Additionally,
this unused position can be grounded to further improve isolation.
FIG. 4 is a diagram illustrating an example of this alternative
embodiment. Referring now to FIG. 4, in this example, the secondary
switches SW12, SW13, SW15 and SW16 include an additional position
that is tied to a signal ground. That is secondary switches SW12,
SW13, SW15 and SW16 each include at least one position for each
branch and at least one additional position that is tied to signal
ground. In operation, when one or more branches of the switchable
diplexer are unused, the secondary switches serving those branches
can be switched to the grounded position, thereby improving the
isolation provided.
[0072] For example, in the embodiment illustrated in the example of
FIG. 4, primary switches SW11 and SW14 are set to select the upper
branches of the switchable diplexer 302. Isolation from these
switches ISO 11 and ISO 14 provides a SW15 and SW16 are set to the
grounded position as shown to provide further signal isolation for
a portion of the signal that might pass through the isolation ISO
11 and ISO14 provided by primary switches SW11 and SW14. Similarly,
if primary switches SW11 and SW14 were set to select the D-band
branches of switchable diplexer 302, then secondary switches SW12
and SW13 could be set to their respective grounded positions to
provide isolation from unwanted signals in those branches.
[0073] In further embodiments, conventional multi-band diplexers
can be combined with switchable diplexers to provide enhanced
functionality. In such embodiments, a combination of bandpass
filters, diplexers and switches are provided to support
communication and selection of multiple bands. For example, in a
video distribution network such as a home or office cable TV
installation, conventional diplexers can be provided to allow CATV
signals to share the coaxial cable runs with MoCA or other network
traffic. These diplexers can also be combined with switching
capability to allow selection of a desired band for network
traffic. In still further embodiments, these diplexers can be
combined with additional filters and switching capabilities to
provide further support for additional network bands.
[0074] FIG. 5 is a diagram illustrating an example implementation
of such a combination of bandpass filters, diplexers and switches
to address multiple bands. The illustrated example supports cable
TV signals as well as the following MoCA bands: Extended-D; D-low;
D-high; E, F and H. This example implementation is now described
with reference to FIG. 5. After reading this description, it will
become apparent to one of ordinary skill in the art how the
combination of diplexers and switches and filters can be
implemented using other filters, other diplexers, and other
arrangements of components. The example of FIG. 5 includes three
bandpass filters 403, 405, and 407, 3 diplexers 410, 411, and 412,
and three switches SW21, SW22, and SW23. E-band bandpass filter 403
as a passband range of 475 675 MHz, F-band bandpass filter 405 has
a passband range of 650 MHz-875 MHz, and H-band bandpass filter 407
has a passband range of 950 MHz-1050 MHz. The cable TV and D-band
frequency bands are accommodated using three diplexers 410, 411 and
412. Diplexers 410, 411, 412 are each configured to handle two
different frequency bands. D-band diplexer 410 is configured to
pass D-band signals from 1125 MHz-1675 MHz, and cable TV signals
below 1002 MHz. D-low band diplexer is configured to pass signals
in the 1125 MHz-1225 MHz passband as well as cable TV signals below
1002 MHz. D-high band diplexer is configured to pass signals in the
1350 MHz-1675 MHz passband and cable TV signals below 1002 MHz. In
other embodiments, the diplexers can include a low-pass filter
configured to have a passband for other TV signals such as, for
example, a passband of less than or equal to 864 MHz.
[0075] The combination diplexer 400 can be used to provide
communications of network signals (such as, for example, MoCA
signals) in combination with cable TV signals. In the illustrated
example, diplexer 400 is connected to the coaxial cable at common
port 422. Common port 422 can be, for example, an F connector at
the wall outlet, or other coaxial cable sourcing cable TV signals
and connected to network equipment. Accordingly combination
diplexer 400 can receive cable TV signals as well as network
signals through common port 422 and distribute cable TV signals and
network signals at its output on the left-hand side of the page.
Although cable TV signals are generally provided in one direction,
networking signals, including the example MoCA network signals, may
involve bidirectional communication.
[0076] With continued reference to FIG. 5, example operational
scenarios are now described. In this example configuration,
switches SW21 and SW23 are single pole-six-throw (SP6T) switches
that can be used to select one of the available communication
bands: E-band, F-band, H-band or the D-bands.
[0077] When either of the D-band, D-low band or D-high band are
selected in this example, cable TV signals at or below 1002 MHz are
also passed through the combination diplexer 400 by the respective
diplexer 410, 411, or 412. Accordingly, switch SW22, which in this
example is a single pole triple throw (SP3T) switch, is used in
conjunction with switches SW21 and SW23 to select the appropriate
diplexer 410, 411, 412 to pass the cable TV signals. In some
embodiments switches SW21, SW23 are configured through mechanical
or electronic coupling to choose the same bandpass filter or
diplexer. In further embodiments switch SW22 is coupled
mechanically or electronically to either or both switches SW2 1,
SW23 such that when a D-band diplexer is selected for network
communications, the same D-band diplexer is selected by SW22 to
allow the cable TV signals to pass through to the set-top box or
other cable TV tuner.
[0078] For example, in some embodiments, switches SW21 and SW22 can
be implemented as a ganged switch or as a double pole switch such
that when one of terminals C, D or E of switch SW21 is selected,
the corresponding terminal A, B or C controller can be used to
control the switching through the use of control signals, and the
control signals can be configured to be sent to switches SW21 and
SW22 to control the switch selection in a coordinated manner.
Accordingly, when the controller causes one of terminals C, D or E
of switch SW21 to be selected, it also causes the corresponding
terminal A, B or C of switch SW22 to be selected. This can be
accomplished by routing the same control signals to both switches,
or by configuring (e.g., programming) the controller to send the
appropriate control signals to both switches to achieve this
coordination.
[0079] In yet another embodiment, the D-band diplexers of the
example in FIG. 5 are replaced by D-band bandpass filters and the
cable TV signals are routed separately. FIG. 6 is a diagram
illustrating an example of a switchable diplexer with a separate
communication path for cable TV signals. Referring now to FIG. 6,
in this example, the switchable diplexer 500 includes six bandpass
filters for communication of 6 network bands, which in this example
are MoCA bands. These bandpass filters are E-band bandpass filter
403, F-band bandpass filter 405, H-band bandpass filter 407, D-band
bandpass filter 414; D-low band bandpass filter 415 and D-high band
bandpass filter 416. Switch SW25, low pass filter 418 and signal
path 422 are provided to allow selection of cable TV signals. In
this embodiment as compared to that of FIG. 5, D-band diplexers are
not used, and instead, D-band bandpass filters are provided to
allow selection of D-band network communications and cable TV low
pass filter is used to allow communication of cable TV signals to a
set top box or other cable TV tuner. As a result, switch SW23 is
not needed and a SPST switch SW24 can be used in its place. Switch
SW24 can be mechanically or electronically coupled to switches
SW21, SW23 to allow common control of the switching.
[0080] FIG. 7 is a diagram illustrating an example of a cascaded
switchable diplexer in accordance with one embodiment of the
systems and methods described herein. Referring now to FIG. 7,
switchable diplexer 600 includes bandpass filters and a diplexer
for communication of 4 network bands, which in this example are
MoCA bands. The bandpass filters are E-band bandpass filter 603 and
F-band bandpass filter 604 for communicating network communications
in the E and F bands. The diplexer in the illustrated example is an
extended D-band diplexer 602 that is configured to pass signals in
the 1125 MHz-1675 MHz range (D-band) through one leg and cable TV
signals below 1002 MHz through the other leg.
[0081] Switches SW31 and SW32 are used to select which of the bands
are passed by switchable diplexer 600. For example, in the
illustrated embodiment switches SW31 and SW32 can select from among
E band, F band and D band.
[0082] A D-low band low pass filter 605 is included in this example
and connected in series with D-band diplexer 602, creating a
cascaded, switchable diplexer enabling selection of a sub-band from
within the passband of D-band diplexer 602.
[0083] Switches SW34 and SW35 are provided to switch a D-low band
low pass filter 605 in or out of the circuit. When switches SW31
and SW32 are configured to route communications through D-band
diplexer 602, switches SW34 and SW35 can be configured to either
pass the signals through D-low band low pass filter 605 or through
shunt 511. When switches SW34 and SW35 are configured to route
signals through D-low band filter 605, the cascaded combination of
D-low band low pass filter 605 and extended D-band diplexer 602
operate to create a D-low band bandpass filter with a passband of
1125 MHz-1225 MHz. When switches SW34 and SFW 35 are configured to
pass the signal through shunt 511, switchable diplexer 600 passes
signals in both the D-low and D-high bands.
[0084] For example, when switches SW34 and SW35 are configured to
switch D-low band low pass filter 605 into the circuit, D-low band
low pass filter 605 effectively stops signals above 1225 MHz. As a
result, the passband of this cascaded combination is 1125 MHz to
1225 MHz.
[0085] Accordingly, the cascaded diplexer includes a diplexer (602
in this example) having a plurality of bandpass filters each having
a passband; and a second bandpass filter (605 in this example)
coupled in series with a bandpass filter in the diplexer.
Preferably, the second bandpass filter has a passband that further
limits the passband of the diplexer. That is the passband of the
series bandpass filter is either a subset of, or overlaps with, the
passband of the bandpass filter in the diplexer. In such
embodiments, when the series bandpass filter is switched into the
circuit, it further limits the passband of the circuit.
[0086] FIG. 8 is a diagram illustrating another example of a
cascaded switchable diplexer in accordance with one embodiment of
the systems and methods described herein. In this example, D-high
band high pass filter 704 with a cutoff frequency of 1350 MHz is
added in parallel to D-low band low pass filter 605. When selected
in conjunction with D-band diplexer 602, this D-high band high pass
filter 704 would operate with extended D-band diplexer 602 as a
D-high band diplexer.
[0087] Although not illustrated in the examples of FIG. 7 or 8, an
H-band bandpass filter could also be included with the switchable
diplexer to allow communication of H-band signals. In such
embodiments, switches SW31 and SW32 can be modified to
single-pole-four-throw switches to accommodate the added leg for
the H-band bandpass filter. Likewise, other bandpass filters could
be added to these or other embodiments described herein.
[0088] Although the example embodiments of FIGS. 7 and 8 are shown
as having one cascaded diplexer circuit leg, it will become
apparent to one of ordinary skill in the art after reading this
disclosure that additional cascaded diplexer circuit legs can be
included in the design. Likewise, the quantity of parallel bandpass
filters (e.g., 403, 405) can be decreased or increased as needed to
accommodate the desired frequency bands. In embodiments where
parallel bandpass filters are eliminated, switches SW3 1, SW32 may
also be eliminated.
[0089] The example switchable diplexers disclosed herein utilize
bandpass filters with passbands suitable for communication in MoCA
bands. It will become apparent to one of ordinary skill in the art
after reading this description that the systems and methods
described herein can be implemented using bandpass filters and
diplexers configured to accommodate different passbands for
communications in different frequency bands or for communications
with different networking standards. It will also be appreciated by
one of ordinary skill in the art that the examples described herein
can be modified with fewer or a greater number of bandpass filters
or diplexers to accommodate more or less different frequency
bands.
[0090] The embodiments described herein with respect to FIGS. 5-8
can be laid out and physically configured in accordance with the
embodiments described with reference to FIGS. 3 and 4. That is, the
filters in the combination diplexers and cascaded diplexers can be
arranged such that filters with like passbands or stop bands can be
arranged adjacent to one another, and filters can be kept
physically separate where one filter's stop band overlaps with
(partially or completely) another filter's passband. Additionally,
where one filter's stop band overlaps with (partially or
completely) another filter's passband, those filters can be placed
on separate secondary switches (e.g., as is the case with F-band
bandpass filter 304 and D-low band bandpass filter 306 in FIG. 3)
to better isolate those filters.
[0091] Although the systems and methods set forth herein are
described in terms of various exemplary embodiments and
implementations, it should be understood that the various features,
aspects and functionality described in one or more of the
individual embodiments are not limited in their applicability to
the particular embodiment with which they are described, but
instead can be applied, alone or in various combinations, to one or
more of the other embodiments, whether or not such embodiments are
described and whether or not such features are presented as being a
part of a described embodiment. Thus, the breadth and scope of the
present invention should not be limited by any of the
above-described exemplary embodiments.
[0092] Terms and phrases used in this document, and variations
thereof, unless otherwise expressly stated, should be construed as
open ended as opposed to limiting. As examples of the foregoing:
the term "including" should be read as meaning "including, without
limitation" or the like; the term "example" is used to provide
exemplary instances of the item in discussion, not an exhaustive or
limiting list thereof; the terms "a" or "an" should be read as
meaning "at least one," "one or more" or the like; and adjectives
such as "conventional," "traditional," "normal," "standard,"
"known" and terms of similar meaning should not be construed as
limiting the item described to a given time period or to an item
available as of a given time. Likewise, where this document refers
to technologies that would be apparent or known to one of ordinary
skill in the art, such technologies encompass those apparent or
known to the skilled artisan now or at any time in the future.
[0093] The presence of broadening words and phrases such as "one or
more," "at least," "but not limited to" or other like phrases in
some instances shall not be read to mean that the narrower case is
intended or required in instances where such broadening phrases may
be absent.
[0094] Additionally, the various embodiments set forth herein are
described in terms of exemplary block diagrams, flow charts and
other illustrations. As will become apparent to one of ordinary
skill in the art after reading this document, the illustrated
embodiments and their various alternatives can be implemented
without confinement to the illustrated examples. For example, block
diagrams and their accompanying description should not be construed
as mandating a particular architecture or configuration.
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