U.S. patent application number 14/803620 was filed with the patent office on 2016-09-01 for termination circuit, and interface circuit and system including the same.
The applicant listed for this patent is SK hynix Inc.. Invention is credited to Hae Kang JUNG.
Application Number | 20160254931 14/803620 |
Document ID | / |
Family ID | 56556034 |
Filed Date | 2016-09-01 |
United States Patent
Application |
20160254931 |
Kind Code |
A1 |
JUNG; Hae Kang |
September 1, 2016 |
TERMINATION CIRCUIT, AND INTERFACE CIRCUIT AND SYSTEM INCLUDING THE
SAME
Abstract
An interface circuit may include a termination resistor and a
termination voltage generation unit. The termination resistor may
be coupled between a reception pad and a termination node. The
termination voltage generation unit may detect a voltage level of
the termination node, and may drive the termination node to a level
of a termination voltage when the voltage level of the termination
node deviates from a predetermined range.
Inventors: |
JUNG; Hae Kang; (Icheon-si
Gyeonggi-do, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SK hynix Inc. |
Icheon-si Gyeonggi-do |
|
KR |
|
|
Family ID: |
56556034 |
Appl. No.: |
14/803620 |
Filed: |
July 20, 2015 |
Current U.S.
Class: |
375/257 |
Current CPC
Class: |
H04L 25/028 20130101;
H04L 25/0278 20130101; H04L 25/0292 20130101; H03K 19/0005
20130101 |
International
Class: |
H04L 25/02 20060101
H04L025/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 27, 2015 |
KR |
10-2015-0028319 |
Claims
1. An interface circuit comprising: a termination resistor coupled
between a reception pad and a termination node; and a termination
voltage generation circuit configured to detect a voltage level of
the termination node, and drive the termination node to a level of
a termination voltage when the voltage level of the termination
node deviates from a predetermined range, wherein the termination
voltage generation circuit comprises a first comparator configured
to compare the voltage level of the termination node and an up
reference voltage, and generate a first comparison signal, a
pull-up driver configured to pull-up drive the termination node in
response to the first comparison signal, a second comparator
configured to compare the voltage level of the termination node and
a down reference voltage, and generate a second comparison signal,
and a pull-down driver configured to pull-down drive the
termination node in response to the second comparison signal,
wherein the pull-up driver comprises a first resistor element
coupled with a power supply voltage, and a first switching element
coupled between the first resistor element and the termination
node, and configured to be turned on in response to the first
comparison signal, wherein the pull-down driver comprises a second
resistor element coupled with a ground voltage, and a second
switching element coupled between the second resistor element and
the termination node, and configured to be turned on in response to
the second comparison signal, wherein an impedance value of the
first resistor element is substantially the same as an impedance
value of the second resistor element, and the impedance values of
the first and second resistor elements are less than the impedance
value of the termination resistor.
2. The interface circuit according to claim 1, further comprising:
a receiver coupled with the reception pad, and configured to
amplify a signal received through the reception pad.
3. The interface circuit according to claim 1, wherein the
termination voltage generation circuit floats the termination node
when the voltage level of the termination node is within the
predetermined range.
4. The interface circuit according to claim 1, wherein the
termination voltage is a middle level between the power supply
voltage and the ground voltage.
5. The interface circuit according to claim 1, further comprising:
a capacitor coupled between the ground voltage and the termination
node.
6. The interface circuit according to claim 5, wherein the
capacitor is configured to stabilize the voltage level of the
termination node by preventing the voltage level of the termination
node from fluctuating in response to a voltage variation, a
temperature variation, or from noise.
7. The interface circuit according to claim 1, further comprising:
a transmission driver coupled to the reception pad, wherein the
transmission driver includes a pull-up transmission driver coupled
between a first power supply voltage and the reception pad, and a
pull-down transmission driver coupled between a ground voltage and
the reception pad, and wherein an impedance value of the
termination resistor corresponds to either a turn-on impedance
value of the pull-up transmission driver or the pull-down
transmission driver.
8-13. (canceled)
14. An interface circuit comprising: a termination resistor coupled
between a reception pad and a termination node; and a termination
voltage generation circuit configured to detect a voltage level of
the termination node, and drive the termination node to a level of
a termination voltage when the voltage level of the termination
node deviates from a predetermined range, wherein the termination
voltage generation circuit comprises a first comparator configured
to compare the voltage level of the termination node and an up
reference voltage, and generate a comparison signal, a second
comparator configured to compare the voltage level of the
termination node and a down reference voltage, and generate the
comparison signal, a pull-up driver configured to pull-up drive the
termination node in response to the comparison signal, and a
pull-down driver configured to pull-down drive the termination node
in response to the comparison signal.
15. The interface circuit according to claim 14, wherein the
comparison signal is enabled when a voltage level of the
termination node is greater than the up reference voltage.
16. The interface circuit according to claim 15, wherein the
comparison signal is enabled when a voltage level of the
termination node is less than the down reference voltage.
17. A system comprising: a transmission device configured to drive
a signal transmission line and transmit a signal; and a reception
device coupled with the signal transmission line, and configured to
receive the signal, the reception device comprising: a termination
resistor coupled between the signal transmission line and a
termination node; and a termination voltage generation circuit
configured to detect a voltage level of the termination node, and
drive the termination node to a level of a termination voltage when
the voltage level of the termination node deviates from a
predetermined range, wherein the termination voltage generation
circuit comprises a first comparator configured to compare the
voltage level of the termination node and an up reference voltage,
and generate a comparison signal, a second comparator configured to
compare the voltage level of the termination node and a down
reference voltage, and generate the comparison signal, a pull-up
driver configured to pull-up drive the termination node in response
to the comparison signal, and a pull-down driver configured to
pull-down drive the termination node in response to the comparison
signal.
18-19. (canceled)
20. The system according to claim 17, further comprising: a
receiver coupled between the signal transmission line and the
termination resistor, and configured to receive a signal
transmitted through the signal transmission line.
21. The system according to claim 17, wherein the termination
voltage generation circuit floats the termination node when the
voltage level of the termination node is within the predetermined
range.
22. The system according to claim 17, wherein the termination
voltage is a middle level between a power supply voltage and a
ground voltage.
23. The interface circuit according to claim 17, further
comprising: a capacitor coupled between a ground voltage and the
termination node.
24. The interface circuit according to claim 23, wherein the
capacitor is configured to stabilize the voltage level of the
termination node by preventing the voltage level of the termination
node from fluctuating in response to a voltage variation, a
temperature variation, or from noise.
25. A termination circuit comprising: a termination resistor; and a
termination voltage generation circuit coupled to the termination
resistor through a termination node, wherein the termination
voltage generation circuit is configured to detect a voltage level
of the termination node, and drive the termination node to a level
of a termination voltage when the voltage level of the termination
node deviates from a predetermined range, wherein the termination
voltage generation circuit comprises a first comparator configured
to compare the voltage level of the termination node and an up
reference voltage, and generate a comparison signal, a second
comparator configured to compare the voltage level of the
termination node and a down reference voltage, and generate the
comparison signal, a pull-up driver configured to pull-up drive the
termination node in response to the comparison signal, and a
pull-down driver configured to pull-down drive the termination node
in response to the comparison signal.
Description
CROSS-REFERENCES TO RELATED APPLICATION
[0001] The present application claims priority under 35 U.S.C.
.sctn.119(a) to Korean application number 10-2015-0028319, filed on
Feb. 27, 2015, in the Korean Intellectual Property Office, which is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] 1. Technical Field
[0003] Various embodiments generally relate to a communication
system. Various embodiments may generally relate to an interface
circuit and/or termination circuit, and system including the
communication system.
[0004] 2. Related Art
[0005] Electronic products for personal uses, such as a personal
computer, a tablet PC, a laptop computer and a smart phone, are
constructed by various electronic components. Two different
electronic components in the electronic products may communicate at
a high speed to process a large amount of data within a short
amount of time. The electronic components generally communicate
through interface circuits.
[0006] As the performances of electronic components are improved,
necessity for a communication scheme capable of increasing a
bandwidth and reducing power consumption is being increased. As
power consumption decreases, the swing widths of signals to be
transmitted through signal transmission lines which couple
electronic components is decreasing. Therefore, in order to ensure
precise transmission of signals, impedance matching of electronic
components for transmitting and receiving signals is important.
SUMMARY
[0007] In an embodiment, an interface circuit may be provided. The
interface circuit may include a termination resistor coupled
between a reception pad and a termination node. The interface
circuit may include a termination voltage generation unit
configured to detect a voltage level of the termination node, and
drive the termination node to a level of a termination voltage when
the voltage level of the termination node deviates from a
predetermined range.
[0008] In an embodiment, a system may be provided. The system may
include a transmission device configured to drive a signal
transmission line and transmit a signal. The system may include a
reception device coupled with the signal transmission line, and may
be configured to receive the signal. The reception device may
include a termination resistor coupled between the signal
transmission line and a termination node. The reception device may
include a termination voltage generation unit configured to detect
a voltage level of the termination node, and drive the termination
node to a level of a termination voltage when the voltage level of
the termination node deviates from a predetermined range.
[0009] In an embodiment, a termination circuit may be provided. The
termination circuit may include a termination resistor. The
termination circuit may include a termination voltage generation
unit coupled to the termination resistor through a termination
node. The termination voltage generation unit may be configured to
detect a voltage level of the termination node, and may drive the
termination node to a level of a termination voltage when the
voltage level of the termination node deviates from a predetermined
range.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a diagram illustrating a representation of an
example of a configuration of a system in accordance with an
embodiment.
[0011] FIG. 2 is a diagram illustrating a representation of an
example of a configuration of a system in accordance with an
embodiment.
[0012] FIG. 3 is a diagram illustrating a representation of an
example of a configuration of a system in accordance with an
embodiment.
[0013] FIG. 4 is a diagram illustrating a representation of an
example of a configuration of the termination voltage generation
unit illustrated in FIG. 3.
[0014] FIG. 5 is a diagram illustrating a representation of an
example of a configuration of the termination voltage generation
unit illustrated in FIG. 3.
[0015] FIG. 6 is a representation of an example of a timing diagram
to assist in the explanation of an operation of a system in
accordance with an embodiment.
DETAILED DESCRIPTION
[0016] Hereinafter, a termination circuit, and an interface circuit
and system including the same will be described below with
reference to the accompanying drawings through various examples of
embodiments.
[0017] In FIG. 1, a system 1 in accordance with an embodiment may
include a master device 110 and a slave device 120. The system 1
may mean, for example, a group of internal components constructing
electronic devices such as, for example but not limited to,
workstations, laptops, client-side terminals, servers, distributed
computing systems, hand-held devices and video game consoles. The
master device 110 and the slave device 120 may form one link.
[0018] The master device 110 may control the operation of the slave
device 120. The master device 110 may execute an operation system
and perform various calculation functions in an electronic device.
For example, the master device 110 may include a processor, and the
processor may include, for example but not limited to, a central
processing unit (CPU), a graphic processing unit (GPU), a
multimedia processor (MMP) or a digital signal processor (DSP). The
master device 110 may be realized in the form of a system-on-chip
(SoC) by combining processor chips having various functions, such
as application processors.
[0019] The slave device 120 may perform various operations by being
controlled by the master device 110. The slave device 120 may
include components. All of the components included in the slave
device 120 operate by being controlled by the master device 110.
For example, the slave device 120 may include, for example but not
limited to, a system memory, a power controller, or a module such
as a communication module, a multimedia module and an input/output
module capable of performing various functions. For instance, the
slave device 120 may be a memory device. The memory device may
include a volatile memory device such as, for example but not
limited to, an SRAM (static RAM), a DRAM (dynamic RAM) and an SDRAM
(synchronous DRAM). The memory device may include at least one of
nonvolatile memory devices such as, for example but not limited to,
a ROM (read only memory), a PROM (programmable ROM), an EEPROM
(electrically erasable and programmable ROM), an EPROM
(electrically programmable ROM), a flash memory, a PRAM (phase
change RAM), an MRAM (magnetic RAM), an RRAM (resistive RAM) and an
FRAM (ferroelectric RAM).
[0020] The master device 110 may be coupled with the slave device
120 through a plurality of buses 130, and thereby form a link. The
master device 110 may transmit signals to the slave device 120,
through the plurality of buses 130. The master device 110 may
receive the signals transmitted from the slave device 120, through
the plurality of buses 130. For example, the plurality of buses 130
may include, but not limited to, signal transmission lines such as
data buses, command buses, address buses and clock buses.
[0021] The master device 110 and the slave device 120 may include
interface circuits 111 and 121, respectively, to reliably perform
communication. The interface circuit 111 of the master device 110
may transmit signals to the slave device 120 and receive the
signals transmitted from the slave device 120, through the buses
130. For example, the interface circuit 111 may convert the signals
used in the master device 110 into signals appropriate to be
transmitted through the buses 130 or convert the signals
transmitted through the buses 130 into signals appropriate to be
used in the master device 110. The interface circuit 121 of the
slave device 120 may receive the signals transmitted from the
master device 110 and transmit signals to the master device 110,
through the buses 130. For example, the interface circuit 121 may
convert the signals transmitted through the buses 130 into signals
appropriate to be used in the slave device 120 or convert the
signals used in the slave device 120 into signals appropriate to be
transmitted through the buses 130. For example, the master device
110 and the slave device 120 may be the components of a system
using a serial communication scheme, and the interface circuits 111
and 121 may include, for example, components such as, but not
limited to, encoding units, decoding units, serialization units and
parallelization units.
[0022] Since the master device 110 and the slave device 120 are
different components constructing one system, impedance matching of
both devices may be needed for reliable communication between the
master device 110 and the slave device 120. As the operation speed
of a system increases and the power consumption of the system
decreases, the swing widths or amplitudes of signals to be
transmitted through the buses 130 are gradually decreasing.
Therefore, it may be necessary that the impedance of the interface
circuit coupled with one ends of the buses 130 correspond to the
impedance of the interface circuit coupled with the other ends of
the buses 130. The interface circuits 111 and 121 may include
termination circuits for such impedance matching. Each termination
circuit may be a circuit to control the impedance of a device for
receiving the signals transmitted through the buses 130, such that
the reception device may have substantially the same impedance as
the impedance of a device for transmitting the signals.
[0023] FIG. 2 is a diagram illustrating a representation of an
example of a configuration of a system 2 in accordance with an
embodiment. The components illustrated on the left side of signal
transmission lines 211 to 214 may be the components of the
interface circuit 111 of the master device 110 (i.e., see FIG. 1).
The components illustrated on the right side of the signal
transmission lines 211 to 214 may be the components of the
interface circuit 121 of the slave device 120 (i.e., see FIG. 1).
When the master device 110 transmits signals to the slave device
120, an interface circuit 201 may be the component of the interface
circuit 111 of the master device 110, and an interface circuit 202
may be the component of the interface circuit 121 of the slave
device 120. Conversely, when the slave device 120 transmits signals
to the master device 110, the interface circuit 201 may be the
component of the interface circuit 121 of the slave device 120, and
the interface circuit 202 may be the component of the interface
circuit 111 of the master device 110.
[0024] The interface circuit 201 may include a plurality of signal
transmission units TX. The plurality of signal transmission units
TX may include a plurality of data transmission units 221 to 223
and a data strobe transmission unit 224. The plurality of data
transmission units 221 to 223 may be respectively coupled with a
plurality of data transmission lines 211 to 213 through data
transmission pads 231 to 233. The plurality of data transmission
units 221 to 223 may drive the data transmission lines 211 to 213
according to the level of data to transmit. For example, in the
case where the level of data to transmit is a logic high, the data
transmission units 221 to 223 may drive the data transmission lines
211 to 213 to a high level. For example, in the case where the
level of data to transmit is a logic low, the data transmission
units 221 to 223 may drive the data transmission lines 211 to 213
to a low level. If the data transmission lines 211 to 213 are
driven by the data transmission units 221 to 223, first to eighth
data DQ0 to DQ7 may be transmitted through the data transmission
lines 211 to 213. The data strobe transmission unit 224 may be
coupled with a data strobe signal transmission line 214 through a
data strobe transmission pad 234. The data strobe transmission unit
224 may transmit a data strobe signal DQS through the data strobe
signal transmission line 214. The data strobe signal DQS, as a
signal capable of being synchronized with timing at which the data
DQ0 to DQ7 are transmitted, is a signal capable of notifying timing
at which the data DQ0 to DQ7 are transmitted, from the interface
circuit 201 of the master device to the interface circuit 202 of
the slave device.
[0025] The interface circuit 202 may include a plurality of
reception pads 241 to 244. The reception pads 241 to 244 are
respectively coupled with the signal transmission lines 211 to 214.
The respective data transmission lines 211 to 213 may be coupled
with termination resistors ZT through the data reception pads 241
to 243. The termination resistors ZT may be coupled between the
data transmission lines 211 to 213 and a termination node VTT. The
interface circuit 202 may include a plurality of signal reception
units RX. The plurality of signal reception units RX may include a
plurality of data reception units 251 to 253 and a data strobe
reception unit 254. The plurality of data reception units 251 to
253 may be coupled with the data transmission lines 211 to 213
through the data reception pads 241 to 243 to receive the data DQ0
to DQ7 transmitted through the data transmission lines 211 to
213.
[0026] The termination resistors ZT may be provided for impedance
matching between the interface circuit 201 and the interface
circuit 202. The termination resistors ZT may have substantially
the same impedance values as the turn-on impedance values of the
data transmission units 221 to 223, respectively. The termination
node VTT may be set to a termination voltage level. The impedance
matching may be completed when the data reception pads 241 to 243
are coupled with the termination resistors ZT and the termination
node VTT is set to the termination voltage level.
[0027] The interface circuit 202 may include a termination voltage
generation unit 250 configured to set the termination node VTT to
the termination voltage level. The termination voltage generation
unit 250 may be coupled with the termination node VTT, and may
detect the voltage level of the termination node VTT. The
termination voltage generation unit 250 may drive the termination
node VTT to the level of a termination voltage when the voltage
level of the termination node VTT deviates from a predetermined
range. The termination voltage generation unit 250 may float the
termination node VTT when the voltage level of the termination node
VTT is within the predetermined range. The termination voltage may
have a certain voltage level between a power supply voltage and a
ground voltage. For example, the termination voltage may have a
level corresponding to the middle level between the power supply
voltage and the ground voltage.
[0028] The interface circuit 202 may include a capacitor element
261. The capacitor element may be coupled with the termination node
VTT. The capacitor element 261 may stabilize the voltage level of
the termination node VTT. The capacitor element 261 may prevent the
voltage level of the termination node VTT from fluctuating due to a
voltage variation, a temperature variation or other noise.
[0029] The interface circuit 202 may include a data strobe
reception pad 244. The data strobe reception pad 244 may be coupled
with the data strobe signal transmission line 214. The data strobe
signal transmission line 214 may be coupled with a termination
resistor ZT through the data strobe reception pad 244. The
termination resistor ZT may be coupled with the termination node
VTT. The data strobe signal transmission line 214 may be coupled
with the data strobe reception unit 254 through the data strobe
reception pad 244. The data strobe reception unit 254 may receive
the data strobe signal DQS transmitted through the data strobe
signal transmission line 214.
[0030] FIG. 3 is a diagram illustrating a representation of an
example of a configuration of a system 3 in accordance with an
embodiment. Referring to FIG. 3, the system 3 may include a
transmission device and a reception device. The transmission device
may include a transmission interface circuit 301, and the reception
device may include a reception interface circuit 302. The
transmission interface circuit 301 may be coupled with the
reception interface circuit 302 through a signal transmission line
303. Referring to FIG. 3, the transmission interface circuit 301
may include a transmission driver 310. The transmission driver 310
may be any one of the data transmission units 221 to 223 and the
data strobe transmission unit 224 illustrated in FIG. 2. The
transmission driver 310 may drive the signal transmission line 303
based on a transmission signal TDQ. For example, the transmission
driver 310 may drive the signal transmission line 303 to a high
level when the transmission signal TDQ is a high level, and may
drive the signal transmission line 303 to a low level when the
transmission signal TDQ is a low level. The transmission driver 310
may be coupled with the signal transmission line 303 through a
transmission pad 320.
[0031] The transmission driver 310 may include a pull-up
transmission driver 311 and a pull-down transmission driver 312.
The pull-up transmission driver 311 may be coupled between the
terminal of a first power supply voltage VDDQ and the transmission
pad 320. The pull-up transmission driver 311 may be turned on in
response to a pull-up transmission control signal PU. The pull-up
transmission driver 311 may pull-up drive the transmission pad 320
and the signal transmission line 303 coupled with the transmission
pad 320, to the level of the first power supply voltage VDDQ. The
pull-down transmission driver 312 may be coupled between the
terminal of a ground voltage VSS and the transmission pad 320. The
pull-down transmission driver 312 may be turned on in response to a
pull-down transmission control signal PD. The pull-down
transmission driver 312 may pull-down drive the transmission pad
320 and the signal transmission line 303 coupled with the
transmission pad 320, to the level of the ground voltage VSS. Each
of the pull-up transmission driver 311 and the pull-down
transmission driver 312 may include an N channel MOS
transistor.
[0032] The transmission interface circuit 301 may include a
pre-driver 330. The pre-driver 330 may generate the transmission
control signals PU and PD based on the transmission signal TDQ. For
example, the pre-driver 330 may drive the pull-up transmission
control signal PU to the level of a second power supply voltage VDD
when the transmission signal TDQ with a high level is received. For
example, the pre-driver 330 may drive the pull-down transmission
control signal PD to the level of the second power supply voltage
VDD when the transmission signal TDQ with a low level is received.
The first power supply voltage VDDQ and the second power supply
voltage VDD may be voltages having substantially the same levels,
but may be voltages which are generated from different power
sources.
[0033] The reception interface circuit 302 may include a
termination resistor ZT and a termination voltage generation unit
350. The termination resistor ZT and the termination voltage
generation unit 350 may construct the termination circuit of the
reception interface circuit 302. The termination resistor ZT may be
coupled between a reception pad 360 and a termination node VTT. The
reception pad 360 may be coupled with the signal transmission line
303. The impedance value of the termination resistor ZT may
correspond to the turn-on impedance value of the pull-up
transmission driver 311 and the pull-down transmission driver 312.
The pull-up transmission driver 311 and the pull-down transmission
driver 312 construct the transmission driver 310. The turn-on
impedance value may be an impedance value that the pull-up
transmission driver 311 and the pull-down transmission driver 312
have when they are turned on. When a signal is transmitted through
the signal transmission line 303, one of either the pull-up
transmission driver 311 or the pull-down transmission driver 312 is
turned on and drives the signal transmission line 303. Thus, the
impedance value of the termination resistor ZT may be substantially
the same as the turn-on impedance value of the pull-up transmission
driver 311 and the pull-down transmission driver 312.
[0034] The termination voltage generation unit 350 may be coupled
with the termination node VTT, and may detect the voltage level of
the termination node VTT. The termination voltage generation unit
350 may drive the termination node VTT to the level of the
termination voltage when the voltage level of the termination node
VTT deviates from a predetermined range. The termination voltage
generation unit 350 may float the termination node VTT when the
voltage level of the termination node VTT is within the
predetermined range. The termination voltage may have a level
corresponding to the middle level between the first power supply
voltage VDDQ and the ground voltage VSS.
[0035] The reception interface circuit 302 may include a receiver
370. The receiver 370 may be coupled with the reception pad 360.
The receiver 370 may amplify the signal transmitted through the
signal transmission line 303, and generate a reception signal RDQ.
Since the reception pad 360 is coupled with the termination
resistor ZT, the receiver 370 may precisely receive the signal
transmitted through the signal transmission line 303 from the
transmission interface circuit 301. The reception interface circuit
302 may include a capacitor element 380. The capacitor element 380
may be coupled between the termination node VTT and the ground
voltage VSS. The capacitor element 380 may stabilize the voltage
level of the termination node VTT. For example, the capacitor
element 380 may prevent the voltage level of the termination node
VTT from fluctuating due to a voltage variation, a temperature
variation or other noise.
[0036] FIG. 4 is a diagram illustrating a representation of an
example of a configuration of the termination voltage generation
unit 350 illustrated in FIG. 3. Referring to FIG. 4, a termination
voltage generation unit 350A may include a first comparator 410, a
pull-up driver 420, a second comparator 430, and a pull-down driver
440. The first comparator 410 may compare the voltage level of the
termination node VTT and an up reference voltage VTTU, and generate
a first comparison signal COM1. The up reference voltage VTTU may
have a level higher than the level of the termination voltage. The
up reference voltage VTTU as a voltage capable of defining the
upper limit of the predetermined range may be set randomly. The
pull-up driver 420 may pull-up drive the termination node VTT in
response to the first comparison signal COM1. The pull-up driver
420 may be coupled between the terminal of the first power supply
voltage VDDQ and the termination node VTT, and may drive the
termination node VTT with the first power supply voltage VDDQ when
being turned on.
[0037] The second comparator 430 may compare the voltage level of
the termination node VTT and a down reference voltage VTTD, and
generate a second comparison signal COM2. The down reference
voltage VTTD may have a level lower than the level of the
termination voltage. The down reference voltage VTTD as a voltage
capable of defining the lower limit of the predetermined range may
be set randomly. The pull-down driver 440 may pull-down drive the
termination node VTT in response to the second comparison signal
COM2. The pull-down driver 440 may be coupled between the terminal
of the ground voltage VSS and the termination node VTT, and may
drive the termination node VTT with the ground voltage VSS when
being turned on.
[0038] Referring to FIG. 4, the pull-up driver 420 may include a
first resistor element R1 and a first switching element S1. The
first resistor element R1 may be coupled with the terminal of the
first power supply voltage VDDQ. The first switching element S1 may
be coupled between the first resistor element R1 and the
termination node VTT, and be turned on in response to the first
comparison signal COM1. The pull-down driver 440 may include a
second resistor element R2 and a second switching element S2. The
second resistor element R2 may be coupled with the terminal of the
ground voltage VSS. The second switching element S2 may be coupled
between the second resistor element R2 and the termination node
VTT, and may be turned on in response to the second comparison
signal COM2. The first and second resistor elements R1 and R2 may
have the same impedance value or substantially the same impedance
value, and may have an impedance value smaller than the impedance
value of the termination resistor ZT.
[0039] FIG. 5 is a diagram illustrating a representation of an
example of a configuration of the termination voltage generation
unit 350 illustrated in FIG. 3. Referring to FIG. 5, a termination
voltage generation unit 350B may include a first comparator 510, a
pull-up driver 520, a second comparator 530, and a pull-down driver
540. The pull-up driver 520 may include a third resistor element R3
and a third switching element S3. The pull-down driver 540 may
include a fourth resistor element R4 and a fourth switching element
S4. The termination voltage generation unit 350B may have
substantially the same configuration as the termination voltage
generation unit 350A illustrated in FIG. 4 except that the output
nodes of the first and second comparators 510 and 530 are coupled
with each other. As the output nodes of the first and second
comparators 510 and 530 are coupled, both the pull-up driver 520
and the pull-down driver 540 may be driven in the example where the
voltage level of the termination node VTT deviates from the
predetermined range. A comparison signal COM may be enabled in the
example where the voltage level of the termination node VTT becomes
higher than the up reference voltage VTTU or becomes lower than the
down reference voltage VTTD. The pull-up driver 520 and the
pull-down driver 540 may drive the termination node VTT with the
first power supply voltage VDDQ and the ground voltage VSS,
respectively, in response to the comparison signal COM.
Accordingly, the termination voltage generation unit 350B may
stably set the voltage level of the termination node VTT to the
termination voltage level by decreasing a switching count.
[0040] FIG. 6 is a representation of an example of a timing diagram
to assist in the explanation of an operation of the system 3 (i.e.,
see FIG. 3) in accordance with an embodiment. Referring to FIG. 6,
the horizontal axis represents time (t) and the vertical axis
represents voltage (v). Line A illustrates the voltage level
variations of the termination node VTT when the termination voltage
generation unit 350 is not coupled with the termination node VTT.
When the termination voltage generation unit 350 is not coupled
with the termination node VTT, the termination voltage may be set
by balanced codes. The balanced codes may mean that the sum of the
logic levels of the plurality of signals transmitted from the
transmission interface circuit 301 is 0. For example, in order to
set the termination voltage, the transmission device may encode the
plurality of signals to be transmitted through the signal
transmission line 303, in such a manner that the sum of the logic
levels of the plurality of signals is 0.
[0041] Referring to FIG. 6, line B illustrates the voltage level
variations of the termination node VTT when the termination voltage
generation unit 350 is coupled with the termination node VTT. The
termination voltage generation unit 350 may pull-up drive or
pull-down drive the termination node VTT when the voltage level of
the termination node VTT deviates from the predetermined range.
Therefore, a time for the termination node VTT to be stabilized to
the level of the termination voltage may be significantly
shortened. The termination voltage generation unit 350 may pull-up
drive or pull-down drive the termination node VTT when the voltage
level of the termination node VTT deviates from the predetermined
range, and may float the termination node VTT when the voltage
level of the termination node VTT is within the predetermined
range. If the termination node VTT is floated, no power consumption
may be induced in the termination voltage generation unit 350.
Therefore, current consumption for setting the termination node VTT
to the level of the termination voltage may be minimized.
[0042] While various embodiments have been described above, it will
be understood to those skilled in the art that the embodiments
described are examples only. Accordingly, the termination circuit,
and the interface circuit and system including the same described
herein should not be limited based on the described
embodiments.
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