U.S. patent application number 12/964553 was filed with the patent office on 2011-04-28 for current consumption reduction with low power amplifier.
This patent application is currently assigned to SONY ERICSSON MOBILE COMMUNICATIONS AB. Invention is credited to William O. Camp, Phillip Marc Johnson, Bogdan TUDOSOIU.
Application Number | 20110096766 12/964553 |
Document ID | / |
Family ID | 38198028 |
Filed Date | 2011-04-28 |
United States Patent
Application |
20110096766 |
Kind Code |
A1 |
TUDOSOIU; Bogdan ; et
al. |
April 28, 2011 |
CURRENT CONSUMPTION REDUCTION WITH LOW POWER AMPLIFIER
Abstract
A transceiver circuit and a method in a wireless communication
network are provided, where a signal power level for a signal
received at the transceiver circuit is measured and compared to a
predefined threshold power level. At least two groups of power
amplifiers may be used, where one group is optimized for high
efficiency above the predefined threshold power level, and one
group is optimized for high efficiency below the predefined
threshold power level. The amplifiers may be used to amplify the
received signal depending on the signal power level in relation to
the predefined power threshold level. The signal may then be
filtered by duplex filters and forwarded to a diversity antenna or
a main antenna where it is transmitted over an air interface.
Inventors: |
TUDOSOIU; Bogdan; (Lund,
SE) ; Johnson; Phillip Marc; (Raleigh, NC) ;
Camp; William O.; (Chapel Hill, NC) |
Assignee: |
SONY ERICSSON MOBILE COMMUNICATIONS
AB
Lund
SE
|
Family ID: |
38198028 |
Appl. No.: |
12/964553 |
Filed: |
December 9, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11755409 |
May 30, 2007 |
7873330 |
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12964553 |
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11565925 |
Dec 1, 2006 |
7738539 |
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11755409 |
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Current U.S.
Class: |
370/342 ;
455/73 |
Current CPC
Class: |
H03F 1/0205 20130101;
H03F 2200/451 20130101; H03F 2200/417 20130101; H03F 2200/465
20130101; H03F 3/211 20130101; H03F 2203/21157 20130101; H03F
1/0277 20130101; H03F 3/24 20130101; H03F 3/189 20130101 |
Class at
Publication: |
370/342 ;
455/73 |
International
Class: |
H04W 88/02 20090101
H04W088/02 |
Claims
1-13. (canceled)
14. A device comprising: a processor to: determine a signal power
for one or more signals to be transmitted, direct the one or more
signals, when the determined signal power is above a particular
power threshold, to one or more first amplifiers with an efficiency
above the particular power threshold and not to one or more second
amplifiers with an efficiency below the particular power threshold,
and direct the one or more signals, when the determined signal
power is below the particular power threshold, to the one or more
second amplifiers and not to the one or more first amplifiers.
15. The device of claim 14, further comprising: filters to separate
the amplified one or more signals to be transmitted from received
signals.
16. The device of claim 14 further comprising, an isolation
arrangement, connected to the one or more first amplifiers and the
one or more second amplifiers, where the isolation arrangement is
to: prevent signal reflections of the one or more signals after
amplification.
17. The device of claim 14, further comprising: a switch to: select
one of a plurality of antennas to transmit the one or more signals
after amplification by either the one or more first amplifiers or
the one or more second amplifiers.
18. The device of claim 17, where the switch is further to connect
another one of the plurality of antennas to ground.
19. The device of claim 17, where the switch includes at least one
of: a single pole single throw switch, a double pole double throw
switch, a single pole double throw switch, a single pole change
over switch, or another type of switch suitable to select among the
plurality of antennas.
20. The device of claim 14, where the one or more signals to be
amplified by one of the one or more first amplifiers or the one or
more second amplifiers include at least one of: wideband carrier
division multiple access (WCDMA) signals, or combined global system
for mobile communications/enhanced data rates for Global Evolution
(GSWEDGE) signals.
21. A method, comprising: receiving, by a device, one or more
signals; determining, by the device, a power at which the one or
more received signals are to be sent; comparing, by the device, the
power at which the one or more received signals are to be sent to a
particular power threshold; when the power, at which the one or
more received signals are to be sent, is above to the particular
power threshold, directing, by the device, the one or more received
signals to one or more first amplifiers with an efficiency above
the particular power threshold power, and not to one or more second
amplifiers with an efficiency below the particular power threshold;
and when the power, at which the one or more received signals are
to be sent, is below the particular power threshold, directing, by
the device, the one or more received signals to the one or more
second amplifiers, and not to the one or more first amplifiers.
22. The method of claim 21, where the one or more signals are
received from other devices in the wireless communication
network.
23. The method of claim 21, further comprising: separating the
received one or more signals, after amplification, from the one or
more received signals prior to amplification.
24. The method of claim 21, further comprising preventing signal
reflections of the received one or more signals after
amplification.
25. The method of claim 21, further comprising: transmitting the at
least one received signals after amplification by a first diversity
antenna and a first main antenna, where the where the one or more
signals are received, from other devices in a wireless
communication network, by at least one of a second diversity
antenna or a second main antenna, where the second diversity
antenna and the second main antenna differ from the first diversity
antenna and the first main antenna.
26. The method of claim 25, further comprising: selecting one of
the first diversity antenna or the first main antenna to transmit
the one or more signals after amplification; and connecting the
non-selected one of the first diversity antenna or the first main
antennas to ground.
27. The method of claim 21, where the one or more signals are one
of: wideband carrier division multiple access (WCDMA) signals, or
combined global system for mobile communications/enhanced data
rates for Global Evolution (GSWEDGE) signals.
28. A non-transient computer-readable medium for storing
instructions executable by a processor in a device, the
instructions comprising: instructions to receive one or more
signals; instructions to determine a power at which the one or more
received signals are to be sent; instructions to compare the power
at which the one or more received signals are to be sent to a
particular power threshold; instructions to direct, when the power,
at which the one or more received signals are to be sent, is above
the particular power threshold, the one or more received signals to
one or more first amplifiers with an efficiency above the
particular power threshold power, and not to one or more second
amplifiers with an efficiency below the particular power threshold;
and instructions to direct, when the power, at which the one or
more received signals are to be sent, is below to the particular
power threshold, the one or more received signals to the one or
more second amplifiers, and not to the one or more first
amplifiers.
29. The non-transient computer-readable medium of claim 28, where
the one or more signals are received from other devices in a
wireless communication network.
30. The non-transient computer-readable medium of claim 28, where
the instructions further comprise: instructions to separate the one
or more received signals, prior to amplification, from the one or
more received signals after amplification.
31. The non-transient computer-readable medium of claim 28, where
the instructions further comprise: instructions to prevent signal
reflections of the one or more received signals after
amplification.
32. The non-transient computer-readable medium of claim 31, where
the instructions further comprise: instructions to transmit the at
least one received signals, after amplification, by a first
diversity antenna and a first main antenna, where the one or more
signals are received, from other devices in a wireless
communication network, by at least one of a second diversity
antenna or a second main antenna, where the second diversity
antenna and the second main antenna differ from the first diversity
antenna and the first main antenna.
33. The non-transient computer-readable medium of claim 32, where
the instructions further comprise: instructions to select one of
the first diversity antenna or the first main antenna to transmit
the one or more received signals, after amplification; and
instructions to connect the non-selected one of the first diversity
antennas or the first main antenna to ground.
Description
RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 11/565,925 entitled Current Consumption
Reduction with Low Power Amplifier filed Dec. 1, 2006, the
disclosure of which is incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to current consumption
reduction in wireless communication networks.
BACKGROUND OF THE INVENTION
[0003] The development of 3G wireless communication networks by
standards, such as HSPDA (High Speed Packet Data Access), EUL
(Enhanced Uplink) will allow for higher data rates on the downlink
channel (from the base station to the mobile station) and on the
uplink channel (from the mobile station to the base station) and
further on towards LTE/SAE (Long-Term Evolution/System Architecture
Evolution).
[0004] HSPDA will, for example, allow for peak data rates up to 10
Mbit/s, shorter connection and response times and a huge increase
in sector throughput, while the EUL will increase uplink data rates
in a later HSPDA release. LTE/SAE, in turn, will offer similar
advantages.
[0005] Nonetheless, while these advantages will benefit end-users
and the use of resource hungry mobile applications, the
improvements are in conflict with other parameters important in
such wireless communication networks, such as current consumption
both in the mobile stations and the base stations, volume, and
others.
[0006] One attempt of dealing with the increased power consumption
is the introduction of power amplifiers adapted to have high
efficiency at high output powers and power amplifiers with high
efficiency at lower output powers as shown in FIG. 1.
[0007] Here, the amplifier circuit comprises one amplifier for high
output power and one for lower output powers, i.e., around 15 dBm.
Even though the current consumption through this arrangement is
reduced with respect to only one power amplifier, there is still
room for reducing the current consumption even more and
particularly for saving battery power in diversity systems, be it
in receiver or transmitter diversity systems, or both.
[0008] Aspects of the invention provide an alternative way of
reducing the current consumption in a mobile station or an access
point in a wireless communication network.
SUMMARY OF THE INVENTION
[0009] One aspect of the invention provides a transceiver for
wireless communication networks. The transceiver comprises: at
least one transceiver module for determining the signal power to be
transmitted; a unit for directing one or more signals whose
determined signal power is above a certain power threshold to one
or more first amplifiers with high efficiency above the power
threshold and one or more signals whose determined signal power is
below the power threshold to one or more second amplifiers with
high efficiency at signal powers below the power threshold; an
isolation arrangement connected to the one or more first amplifiers
for preventing signal reflections of the signals amplified by the
one or more first amplifiers; and at least one first diversity
antenna and at least one first main antenna for transmitting the
amplified signals.
[0010] One advantage of the transceivers according to the present
invention is the tangible reduction in current consumption and the
flexibility of its use in virtually any diversity transceiver
circuit.
[0011] Furthermore, another aspect of the invention provides a
method for amplifying signals in a wireless communication network
which comprises the steps of: a) receiving one or more signals, b)
determining the power at which the one or more received signals are
to be sent, c) comparing the power at which the one or more
received signals are to be sent to a predefined power threshold, d)
directing one or more signals whose power is above a certain power
threshold to one or more first amplifiers with high efficiency
above the power threshold power, and one or more signals below the
power threshold to one or more second amplifiers with high
efficiency at signal powers below the power threshold, e)
amplifying the signal in the one or more first amplifiers, f)
sending the amplified signal to at least one first diversity
antenna or to at least one main antenna and g) transmitting the one
or more signals over the radio interface via the at least one first
diversity antenna or at least one first main antenna.
[0012] The method may be specially adapted to be implemented by the
transceiver according to the present invention. Also, the steps of
the method according to the present invention may be executed by a
computer program running either on the transceiver of the present
invention or on a separate storage medium.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 illustrates an amplifier circuit according to known
technology.
[0014] FIG. 2 illustrates a transceiver circuit according to a
first embodiment of the present invention.
[0015] FIG. 3 illustrates a transceiver circuit according to a
second embodiment of the present invention, where the transceiver
comprises a DPDT switch.
[0016] FIG. 4 illustrates a transceiver circuit in a MIMO (Multiple
Input Multiple Output) or MISO (Multiple Input Single Output)
system according to a third embodiment of the present
invention.
[0017] FIG. 5 illustrates the steps of a method according to one
embodiment of the present invention.
[0018] FIG. 6 shows a probability versus output power distribution
in a CDMA2000 network.
[0019] FIG. 7 shows a graph where the current consumption is shown
as a function of output power for a transceiver according to the
present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0020] In the following detailed description, reference numbers
depicting identical elements in different figures will not be
repeated for each figure for the purposes of easier reading.
[0021] FIG. 1 gives an illustration of an amplifier circuit 100
where it is attempted to reduce the current consumption in a mobile
station or base station according to known technology.
[0022] Referring to FIG. 1, an RF input signal 110 is fed into a
splitter 140 and directed to the input of a first power amplifier
150 and a second amplifier 160. The first amplifier 150 is trimmed
for high efficiency at high output powers, while the second
amplifier 160 is adapted for high efficiency at lower output
powers, such as, for example, 15 dBm or lower.
[0023] Depending on whether it is desired to output only the high
power amplified RF signal from the first amplifier 150 or the lower
power amplified RF signal from the second amplifier 160, a mode
splitter 110 uses a control signal to make either the first
amplifier 150 or the second amplifier 160 output the amplified
signal. The two control signals used for controlling the power
amplifier outputs are a first mode signal 120 and a second mode
signal 130 corresponding to high power RF signals and lower power
RF signals. Naturally, it may also be possible to combine both the
amplified high power part of the input RF signal and the lower
power part RF input signal in a combiner 170 in an amplified RF
output signal 180.
[0024] It should be noted that normally, the transceiver according
to the present invention illustrated in FIGS. 2-5 may be
implemented in any mobile device operating in a wireless
communication network, such as a mobile station, a wireless network
card, PDA and similar devices, as well as in a base station, access
point, Node B or similar access points in a wireless communication
network.
[0025] Turning now to FIG. 2, a transceiver circuit 200 according
to a first embodiment of the present invention is shown.
[0026] The transceiver circuit 200 comprises a diversity
transceiver module 212 which among other things is used for
determining the power level at which a signal arriving at a power
amplifier is going to be transmitted. This power level is
determined from a signal continuously sent by a base station (not
shown) telling the terminal to either decrease or increase its
output power. Furthermore, the diversity transceiver module 212 is
connected to a first group of power amplifiers (in this case three)
220, 222, 224 trimmed for high efficiency at high output powers,
such as, for example 24 dBm or above. Also, the first group of
power amplifiers 220, 222, 224 for high output powers may each be
connected to a first group of circulators 230, 232, 234
(illustrated by dashed lines in FIG. 2) having among other things
the function of an isolator for preventing signal reflections of an
RF signal from the first antenna circuit 246. Using a circulator as
an isolation circuit would reduce the output power by approximately
0.4 dB. It is however perfectly possible to have a functioning
first group of power amplifiers 220, 222, 224 without using the
circulators 230, 232, 234.
[0027] Each circulator 230, 232, 234, is in turn connected to a
first group of duplexers 240, 242, 244 which may comprise band pass
filters for signals to be transmitted over the air interface and
band pass filters for signals received over the same. These
duplexers additionally provide high isolation between bands of
interest and are therefore used for filtering the interesting part
of the signal.
[0028] It should be mentioned here, that it is assumed that the
signals to be amplified are Wideband Carrier Division Multiplex
Multiple Access (WCDMA) or 3G signals to be sent over the air
interface. However, it is also possible to feed combined GSM/EDGE
and WCDMA signals as well as Long Term Evolution (LTE)-signals,
such as Orthogonal Frequency Division Multiplex (OFDM) or Single
Carrier-Frequency Division Multiple Access (SC-FDMA) to the first
group of power amplifiers 220, 222 and 224 if the bandpass
frequency filters 236, 237 and 238 are designed with a wide enough
pass band.
[0029] Alternatively, the GSM/EDGE signals 249 which are not
amplified by the first group of power amplifiers 220, 222, 224 may
be fed directly into a diversity front-end module or, for example,
a SPnT switch 246 before they are to be sent over the air interface
via the diversity antenna 248. Here an SPnT switch is a Single-Pole
N Throw switch, N being the number of switching positions for the
switch.
[0030] Also, the amplified and filtered radio signals are fed into
the diversity front-end module 246 and sent over the air interface
via the diversity antenna 248.
[0031] Furthermore, radio signals received from the diversity
antenna 248 are filtered by the same first group of frequency
filters 236, 237, 238 as above for removing undesired parts of the
frequency spectrum before they are sent to the diversity
transceiver module 212 via the connections 240, 242 and 244.
[0032] The main transceiver module 252 is connected in a very
similar way to the second front-end module 286. Since the output
power for the radio signals amplified in a second group of
amplifiers 260, 262, 264 is lower than the output power for the
radio signals amplified by the first group of amplifiers 220, 222,
224, isolators in the form of circulators (indicated by dashed
lines) may not be needed either. It may be mentioned that depending
on the output capabilities of the power amplifiers 220, 222, 224,
i.e., the headroom between their maximum output capabilities and
the highest power they will operate at, the ACLR (Adjacent Channel
Leakage Ratio) and the EVM (Error Vector Magnitude) which describe
the interference from neighboring channels to the amplified radio
channels and the modulation distortion induced by interference from
other channels may be reduced.
[0033] It should also be mentioned that the second group of
amplifiers 260, 262, 264 are trimmed for high efficiency at lower
power levels, such as, for example, 15 dBm or lower.
[0034] Additionally, the second group of amplifiers 260, 262, 264
is in turn connected to a second group of bandpass frequency
filters 270, 272, 274. As described previously, these bandpass
filters filter the interesting parts of the frequency spectrum for
the amplified radio signals before they are sent to the main
front-end module 286 and further over the radio interface via the
main antenna 288.
[0035] Radio signals received on the main antenna 288 are also
bandpass filtered by the second group of bandpass frequency filters
before being forwarded as filtered signals 280, 282, 284 to the
main transceiver module 252.
[0036] GSM/EDGE signals 290 not intended to be amplified by the
second group of amplifiers 260, 262, 264 are fed via a separate
input into the main front-end module and sent over the radio
interface via the main antenna 288.
[0037] In case only WCDMA signals are to be amplified by the first
group of amplifiers 220, 222, 224 and the second group of
amplifiers 262, 264, 266, GSM/EDGE signals are fed out from the
main front-end module 286 via a separate output 292.
[0038] FIG. 3 illustrates a transceiver circuit 300 according to a
second embodiment of the present invention. Essentially, it is the
same transceiver circuit 200 from FIG. 2 with the addition of a
switch 320, which, for example may be a Double Pole Double Throw
(DPDT) switch. The function of the elements present from FIG. 2
present in FIG. 2 will not be repeated here.
[0039] A DPDT switch usually consists of two switches switching
between two well-defined states as is known to the skilled person.
The DPDT switch 320 may be provided as a solid state switch or as
an electrical switch, as preferred.
[0040] DPDT switch 320 may, depending on the control signal 311,
activate the main antenna 288 and put the diversity antenna 248 to
ground 310, 312 or vice versa. In this fashion one of the
transmitters can be connected to any one of the two antennas 248,
288. Usually, the main antenna 288 operates at a higher gain than
the diversity antenna 248, so at the lower power levels, where the
use of transmit diversity may not be necessary, the DPDT switch 320
may be used to connect the second group of amplifiers 260, 262, 264
having high efficiency at lower transmit powers to the main antenna
288.
[0041] The active antenna may be coupled to one of the transceiver
circuits; either the diversity transceiver circuit 212 or the main
transceiver circuit 252. However, it may also be possible to couple
one of the antennas to the outputs of both transceiver circuits by
using other types of switches.
[0042] Additionally, one may use other types of switches, such as a
Singe-Pole Single Throw (SPST) switches, (Double Pole Double Throw
(DPDT) switches, Single-Pole Double Throw (SPDT) switches,
Single-Pole Change Over (SPCO) switches and other types of switches
suitable for switching between the one first diversity antenna 248
and the one first main antenna 288.
[0043] Turning now to FIG. 4, a transceiver circuit 400 according
to a third embodiment of the present invention is illustrated. In
this embodiment, we have the same transceiver as in FIG. 2 applied
to a multiple input, multiple output (MIMO) or a multiple input,
single output (MISO) system.
[0044] In contrast to the embodiments in FIGS. 2 and 3, each front
end module 246, 286 has its own receiver antennas 248, 288 and
transmitter antennas 448, 488. Thus, since signals are transmitted
and received via different antennas, frequency filters 236, 237,
238 and 270, 272, 274 for separation of uplink from downlink
signals may no longer be needed, thus they are not illustrated in
FIG. 4.
[0045] The example MIMO or MISO transceiver system 400 may of
course comprise more than two sets of receiver and transmitter
antennas 248, 288 and 448, 488, depending on the application.
[0046] FIG. 5 illustrates the steps of a method according to one
embodiment of the present invention. At step 500, one or more
signals to be transmitted are received at a transceiver circuit
which may be one of the transceiver circuits 200, 300 or 400
described above or some modification of these circuits consistent
with aspects of the transceiver circuits described above and
consistent with the present invention.
[0047] Next, at step 510, in one of the transceiver modules 212,
252 the power level at which the one or more of the signals are
going to be transmitted, is determined. Thereafter at step 520, the
determined signal power level for the one or more signals to be
transmitted is compared with a predefined threshold power value.
This threshold power value is chosen so that the first one group of
amplifiers 220, 222, 224 is adapted to have maximum efficiency
above this value, while the second one group of amplifiers 260,
262, 254 is adapted for maximum efficiency below the threshold
power value. The comparison step 520 is needed to determine to
which group of amplifiers the one or more signals should be sent in
order to be amplified.
[0048] Therefore, if the signal power value for the one or more
received signals is above the predefined threshold value, it is
sent to the first one group of amplifiers 220, 222, 224 at step
530.
[0049] Thereafter, at step 540 the one or more received signals are
amplified by the first one group of amplifiers 220, 222, 224 and
sent further at step 540 to the diversity antenna 248 where they
are transmitted over the air interface at step 550.
[0050] In contrast, if the signal power for the one or more signals
to be transmitted is determined to be below the predefined
threshold power value, the one or more signals are forwarded to the
second one group of amplifiers 260, 262, 264 at step 525.
Thereafter, the one or more signals are amplified by the second
group of amplifiers 260, 262, 264 at step 535 and sent to the main
antenna 288 at step 545.
[0051] It will be appreciated here, that in at least one embodiment
of the transceiver according to the present invention (e.g., the
second embodiment), the amplified one or more signals may be sent
to either the diversity antenna 248 or the main antenna 288, as
preferred.
[0052] Finally, at step 550 the thus amplified one or more signals
are transmitted over the air interface via the main antenna
288.
[0053] FIG. 6 illustrates a probability versus output power
distribution 610 taken from suburban profile measurements for the
CDMA2000 system. The diagram shows the probability in percent of a
certain output power expressed in dBm. Values above 24 dBm are not
shown due to the power class constraints, meaning a transceiver
sending WCMDA signals is not allowed to send signals with higher
than 24 dBm+1/-3 dB (power class 3 constraint). As can be seen from
the diagram, the output power will be mostly concentrated between
-20 dBm and 15 dBm with a slight tail between 15 dBm and 25
dBm.
[0054] These figures are known to the skilled person and have been
arrived at by experiment in many wireless networks in dedicated
mode and are used in cell planning.
[0055] Using these figures however, simulations on the transceiver
circuit according to the present invention have been performed with
varying maximum power values for which the efficiencies of second
group of power amplifiers 260, 262, 264 have been optimized.
[0056] The result of these simulations is shown in the graph in
FIG. 7. Referring to FIG. 7, the graph shows the current
consumption in mA as a function of output power in dBm for three
scenarios. The first scenario comprised the use of a single power
amplifier with maximum efficiency at maximum power and is
illustrated by the curve 710.
[0057] It is evident that the current consumption lies around 0.8
mA for an output power in the interval -18 dBm to 16 dBm, while it
rapidly rises between for output powers beyond 16 dBm.
[0058] The second scenario comprised two power amplifier groups,
where the first group comprised power amplifiers trimmed for high
efficiency at output powers above 15 dBm and power amplifiers
trimmed for high efficiency at output power up to 15 dBm which is
illustrated by the curve 720.
[0059] It is clearly visible that the average current consumption
in the interval between -18 dBm and 15 dBm lies around 0.2 mA,
before rapidly rising for an output effect beyond 15 dBm in a
similar way as for the first scenario. The sudden jump in current
consumption in the region between 15 dBm and 17 dBm may be
explained by the fact that in this region the amplification
switches from the lower power Power amplifier (PA) to the high
power PA.
[0060] Finally, the third situation comprised a high power PA and a
lower power PA with trimmed efficiency up to 9 dBm represented by
the curve 730.
[0061] The sudden increase in current consumption is similar to the
second scenario but (logically) kicks in between 9 dBm and 11 dBm.
Later on, at around 16 dBm output power, the increase in current
consumption becomes identical to the first and second
scenarios.
[0062] Using known formulas for calculating the current consumption
probability for all three scenarios, it was found that the average
current consumption for the second and third scenarios where lower
power PA optimized for high efficiency at lower powers are used,
was reduced by 16 mA compared to the case of only one power
amplifier at maximum output power. However the difference in
current consumption between the second and third cases was only
marginal.
[0063] It may be added that the transceiver according to the
present invention may be employed in any wireless communication
system, such as, for example, GSM, WCDMA, CDMA2000, Wireless Local
Area Network (WLAN SPST), such as IEEE 802.11a, IEEE 802.11b, IEEE
802.11g, HiperLAN, WINNER, WiMAX and other similar wireless
communication systems.
[0064] Also the power amplifiers may consist of one amplifier
component which usually is a solid state component, or comprise
more than one amplifier component, depending on need. Although some
power levels at which the power amplifiers have been designed to be
highly efficient have been mentioned earlier in the description,
they are given as example values only. It should be understood that
the specific power levels for which the PAs are designed to be
highly efficient depend on the application field and therefore may
vary.
[0065] It should be emphasized that the term "comprises/comprising"
when used in this specification is taken to specify the presence of
stated features, integers, steps, or components, but does not
preclude the presence or addition of one or more other features,
integers, steps, components, or groups thereof.
[0066] No element, act, or instruction used in the description of
the present application should be construed as critical or
essential to the invention unless explicitly described as such.
Also, as used herein, the article "a" is intended to include one or
more items. Where only one item is intended, the term "one" or
similar language is used. Further, the phrase "based on," as used
herein is intended to mean "based, at least in part, on" unless
explicitly stated otherwise.
[0067] The scope of the invention is defined by the claims and
their equivalents.
* * * * *