WO1999012262A1 - Emetteur de donnees - Google Patents
Emetteur de donnees Download PDFInfo
- Publication number
- WO1999012262A1 WO1999012262A1 PCT/JP1998/003896 JP9803896W WO9912262A1 WO 1999012262 A1 WO1999012262 A1 WO 1999012262A1 JP 9803896 W JP9803896 W JP 9803896W WO 9912262 A1 WO9912262 A1 WO 9912262A1
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- WO
- WIPO (PCT)
- Prior art keywords
- potential
- diode
- transmission line
- data
- impedance element
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
- H03K19/0175—Coupling arrangements; Interface arrangements
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
- H03K19/0175—Coupling arrangements; Interface arrangements
- H03K19/017545—Coupling arrangements; Impedance matching circuits
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
- H03K19/0008—Arrangements for reducing power consumption
- H03K19/0013—Arrangements for reducing power consumption in field effect transistor circuits
Definitions
- the present invention relates to a data transmission device for transmitting data from a driver to a receiver via a transmission line.
- FIG. 11 shows a configuration of a conventional data transmission device 200.
- the data transmission device 200 is composed of a driver 210 for transmitting data, a receiver 220 for receiving data transmitted by the driver 210, and a receiver for receiving dryno 210. And a transmission line 230 that connects the transmission line 230 and the transmission line 230.
- the data is transmitted from the driver 210 to the receiver 220 via the transmission line 230.
- the driver 210 has an output buffer 212 that outputs data to the transmission line 230.
- the output buffer 211 is connected to the transmission line 230 via the pad 214.
- the receiver 220 has an input buffer 222 that receives the data from the transmission line 230.
- One input of the input buffer 222 is connected to a transmission line 230 through a pad 222 and a stub resistor 232.
- One end of the terminating resistor 240 is connected to the end of the transmission line 230 on the receiver 220 side.
- the other end of the terminating resistor 240 is connected to the terminating potential V term .
- the amplitude of the data on the transmission line 230 is determined by the resistance value of the terminating resistor 240 and the output impedance of the driver 210. Therefore, by appropriately designing the resistance value of the terminating resistor 240 and the output impedance of the driver 210, the amplitude of data on the transmission line 230 can be limited to a sufficiently small amplitude.
- the resistance value of the terminating resistor 240 is equal to the characteristic impedance Z of the transmission line 230. It is determined to be substantially equal. This prevents data transmitted from the driver 210 from being reflected at the end of the transmission line 230 on the receiver 220 side.
- the driver 21 when the driver 210 outputs high-level data, the driver 21
- the output impedance of 0 and the output impedance of the driver 210 when the driver 210 outputs low-level data do not always match. If these do not match, the DC current flowing from the driver 210 to the terminal potential V te rm (I s. U rce) of the absolute value and the DC current flowing from the terminal potential V 'ierm the driver 210 (I si nk) Absolute It is not the same as the value.
- end potential V te rm when the driver 210 is an amplitude value and the driver 210 of the potential of the transmission line 230 from the terminal potential V te rm when outputting the high level data has output Isseki de mouth first level And the amplitude value of the potential of the transmission line 230 differs from the current value.
- the terminal potential V term shifts from the median between the potential corresponding to high-level data (Hi potential) and the potential corresponding to low-level data (Lo potential).
- Hi potential high-level data
- Lo potential low-level data
- the receiver 220 determines whether the data on the transmission line 230 is at a high level or a low level using the terminal potential V term as a reference potential. Therefore, when the terminating potential V term is shifted from the median between the Hi potential and the Lo potential, the time when data changes from low to high and the data changes from high to low. The time to transition to one level will be different. This causes skew when the receiver 220 latches the data on the transmission line 230 in synchronization with a predetermined peak signal.
- An object of the present invention is to provide a data transmission device that reduces consumed power.
- Another object of the present invention is to provide a data transmission device that suppresses the occurrence of skew. Disclosure of the invention
- a data transmission device includes: a driver that transmits data; a receiver that receives data transmitted by the driver; a transmission line that connects the driver and the receiver; A variable impedance element having an impedance value, wherein the variable impedance element is connected to the transmission line.
- the impedance value of the variable impedance element by controlling the impedance value of the variable impedance element, reduction of power consumption and prevention of skew can be optimized. For example, when the data transmission device operates at a low speed, skew hardly occurs. Therefore, in this case, the impedance value of the variable impedance element is controlled so that the impedance value of the variable impedance element increases. As a result, the DC current flowing through the transmission line can be suppressed. As a result, power consumed by the data transmission device can be reduced. High speed data transmission equipment When operating, skew is likely to occur. Therefore, in this case, the impedance value of the variable impedance element is controlled such that the impedance value of the variable impedance element matches the impedance value of the transmission line. Thereby, reflection of data at the end of the transmission line can be suppressed. As a result, the occurrence of skew is suppressed.
- the impedance value of the variable impedance element may change according to the potential of the transmission line.
- the impedance value of the variable impedance element may be controlled so that the impedance value of the variable impedance element increases. This makes it possible to make a fast transition from low level to high level (or from high level to low level). Further, when the potential difference between the potential of the transmission line and the terminal potential is larger than a predetermined value, the impedance value of the variable impedance element may be controlled so that the impedance value of the variable impedance element becomes low. As a result, the amplitude of the data is limited and the reflection of the data is suppressed.
- the impedance value of the variable impedance element may change according to a control signal input from outside the variable impedance element.
- variable impedance element when transmitting data at high speed, a control signal requesting that the impedance value of the variable impedance element be set low is input to the variable impedance element.
- the variable impedance element lowers the impedance value in response to the control signal. This makes it possible to suppress data reflection at the end of the transmission line. As a result, skewing is suppressed.
- a control signal requesting that the impedance value of the variable impedance element be set high is input to the variable impedance element.
- the variable impedance element increases the impedance value in response to the control signal. As a result, the DC current flowing through the transmission line can be suppressed. As a result, data transmission The power consumed by the transmission device can be reduced.
- the impedance value of the variable impedance element and the output impedance of the driver may change so as to be correlated.
- the output impedance of the driver may change according to the impedance value of the variable impedance element.
- the impedance of the variable impedance element when transmitting data at a low speed during standby for data transmission, the impedance of the variable impedance element is set high.
- the output impedance of the driver is set high in response to the impedance of the variable impedance element being set high.
- the level of the Hi potential corresponding to the high-level data and the level of the Lo potential corresponding to the low-level data are substantially the same as when the impedance value of the variable impedance element is set low. It can be the same value. This makes it easier for the receiver to determine whether the transmitted data is high or low.
- the variable impedance element may include a first diode and a second diode connected in parallel. The direction of the current flowing through the first diode is opposite to the direction of the current flowing through the second diode.
- the impedance value of the variable impedance element is very high until one of the first diode and the second diode is biased in the forward direction, and either the first diode or the second diode is not used. If one of them is biased forward, the impedance value of the variable impedance element becomes very low.
- V term indicates a terminal potential
- V f indicates a forward voltage of the first diode and the second diode.
- the impedance value of the variable impedance element is set to be high. Therefore, the only driving load on the driver during the data transition is the capacitance of the transmission line. Therefore, the night will transit at a constant speed. This also helps to reduce the occurrence of skew.
- variable impedance element may further include a resistor connected in series with the first diode and the second diode connected in parallel.
- the impedance value when the first diode or the second diode is biased in the forward direction can be adjusted.
- the resistance value of the resistor is set to be substantially equal to the characteristic impedance of the transmission line, and the forward voltage of the first diode and the second diode is determined by the driver It may be set so as to be substantially equal to the amplitude value of the potential of the transmission line from a predetermined terminal potential when the data is output.
- the variable state in the state where either the first diode or the second diode is forward-biased is set.
- the impedance value of the impedance element becomes substantially equal to the characteristic impedance of the transmission line.
- the amplitude value of the potential of the transmission line from the terminal potential is substantially equal to the forward voltage of the first diode and the second diode.
- Another data transmission device of the present invention includes a driver for transmitting data, and the driver A first transmission line and a second transmission line connecting the driver and the receiver, and a first variable impedance element having a variably controllable first impedance value.
- reduction of power consumption and prevention of skew can be optimized by controlling the impedance value of the first variable impedance element and the impedance value of the second variable impedance element.
- the first variable impedance element includes a first diode and a second diode, an anode of the first diode is connected to a predetermined first potential, and a force source of the first diode is The second diode is connected to the first transmission line, the anode of the second diode is connected to the first transmission line, and the cathode of the second diode is connected to the predetermined second potential lower than the predetermined first potential.
- a sum of the forward voltage of the first diode and the forward voltage of the second diode is determined by a potential difference between the predetermined first potential and the predetermined second potential.
- the second variable impedance element includes a third diode and a fourth diode, an anode of the third diode is connected to a predetermined third potential, and a cathode of the third diode is:Connected to the second ⁇ transmission line, the anode of the fourth diode is connected to the second transmission line, and the cathode of the fourth diode has a predetermined potential lower than the predetermined third potential. Connected to a fourth potential, wherein the sum of the forward voltage of the third diode and the forward voltage of the fourth diode is between the predetermined third potential and the predetermined fourth potential. It may be larger than the potential difference.
- V terrm represents the first potential
- V 5S represents the second potential
- V f represents the forward voltage of the first diode and the second diode.
- the first diode or the second diode becomes forward.
- the first diode or the second diode becomes forward.
- the first diode or the second diode becomes forward.
- the first diode or the second diode becomes forward.
- the first diode or the second diode becomes forward.
- the transmission line is, that Do and being connected via an element having a very low impedance value to the potential V te rml or potential V ss.
- the Hi potential corresponding to the high-level data overnight and the Lo potential corresponding to the mouth-level data become the potential (V terml — V f ) and the potential (V ss + V f ), respectively. Is clamped near. This limits the data amplitude.
- FIG. 1 is a diagram showing a configuration of the data transmission device 1a according to the first embodiment of the present invention.
- FIG. 2 is a diagram showing a transition of the potential of the transmission line 30 shown in FIG.
- FIG. 3 is a diagram showing a temporal change in the output impedance of the driver 10 and the impedance value of the variable impedance element 40.
- FIG. 4D is a diagram illustrating a configuration of the data transmission device 1b according to the first embodiment of the present invention.
- FIG. 4B is a diagram showing a configuration of the data transmission device 1c according to the first embodiment of the present invention.
- FIG. 5A is a diagram showing a configuration of the variable impedance element 42 shown in FIG. 4A.
- FIG. 5B is a diagram showing a configuration of the variable impedance element 44 shown in FIG. 4B.
- FIG. 6 is a diagram showing a configuration of the output buffer 12a of the driver 10.
- FIG. 7A is a diagram showing a configuration of the variable impedance element 46.
- FIG. 7B is a diagram showing a configuration of the variable impedance element 48.
- FIG. 8A is a diagram showing a configuration of a data transmission device 2a according to the second embodiment of the present invention.
- FIG. 8B is a diagram showing the impedance characteristics of diodes 181-1 to 84-4.
- FIG. 9 is a diagram showing a configuration of the data transmission device 2b according to the second embodiment of the present invention.
- FIG. 10 is a diagram showing a configuration of a data transmission device according to another embodiment of the present invention.
- FIG. 11 is a diagram showing a configuration of a conventional data transmission device 200. As shown in FIG.
- FIG. 12 is a diagram showing the transition of the potential of the transmission line 230 shown in FIG. BEST MODE FOR CARRYING OUT THE INVENTION
- FIG. 1 shows a configuration of a data transmission device 1a according to the first embodiment of the present invention.
- the data transmission device la includes a driver 10 for transmitting data, a receiver 20 for receiving data transmitted by the driver 10, and a transmission line 30 for connecting the driver 10 and the receiver 20. including. Data is transmitted from the driver 10 to the receiver 30 via the transmission line 30.
- Each of the driver 10 and the receiver 20 is, for example, a semiconductor integrated circuit.
- the data transmission device 1a further includes a variable impedance element 40 whose impedance value automatically changes according to the potential of the transmission line 30.
- One end of the variable impedance element 40 is connected to an end of the transmission line 30 on the receiver 20 side.
- the other end of the variable impedance element 40 is connected to the terminating potential V term .
- the driver 10 has an output buffer 12 for outputting data to the transmission line 30.
- the output buffer 12 is connected to the transmission line 30 via the pad 14.
- the output buffer 12 is a push-pull type buffer.
- Output buffer 12 is composed of PMOS transistor 71p and NMOS transistor Star 7 In.
- Predetermined logic determined by the NAND element 73, the NOR element 74, and the operational amplifiers 75 and 76 is input to the gates of the transistors 71p and 7In.
- the operational amplifier 75 receives the potential of the transmission line 30 and the reference potential.
- the operational amplifier 76, the potential of the transmission line 30 and the reference potential VR 2 is inputted.
- the transistor 71p In the initial state, the transistor 71p is off, and the transistor 71 ⁇ is off. In this initial state, when data Data having the value "1" is input to the output buffer 12, the transistor 71p is turned on. Transistor 71 n remains off. As a result, the potential of the transmission line 30 is increased so as to approach the predetermined potential V c eQ. Thereafter, when the potential of the transmission line 30 exceeds the reference potential VI ⁇ , the transistor 71p is turned off. Transistor 71 n remains off. This is because, when the potential of the transmission line 30 exceeds the reference potential VRi, the output of the operational amplifier 75 becomes a single level, and as a result, the gate of the transistor 71p becomes a high level.
- the transistor 71p In the initial state, the transistor 71p is off, and the transistor 71 ⁇ is off. In this initial state, when data D ata having a value “0” is input to the output buffer 12, the transistor 71 n is turned on. Transistor 71p remains off. As a result, the potential of the transmission line 30 is lowered so as to approach the predetermined potential V s SQ. After, if falls below the reference potential VR 2 potential of the transmission line 30, the transistor 71 n is turned off. Transistor 71p remains off. When the potential of the transmission line 30 is lower than the reference potential VR 2, the output of the operational amplifier 76 becomes high level, as a result, the gate of the transistor 71 n is from mouth first level and ing.
- the receiver 20 has an input buffer 22 that receives data from a transmission line 30.
- the input buffer 22 is, for example, a two-input operational amplifier.
- One input of the input buffer 22 is connected to the transmission line 30 via a pad 24, a stub resistor 32 and a resistor 31.
- the other input of the input buffer 22 is connected to the terminal potential Vtefm .
- End potential V te rm for example, Ru 1. IV der.
- the input buffer 22 determines whether the data on the transmission line 30 is at a high level or at a single level using the terminal potential V term as a reference potential. In this way, the input buffer 22 receives the data transmitted from the output buffer 12. It may be provided independently of the node having the same potential as the potential of the terminal potential V te rm a terminal potential V te rm. In this case, the input buffer 22 can determine whether the data on the transmission line 30 is at a high level or at a single level using the potential of this node as a reference potential. This allows the input buffer 22 to prevent the influence of noisyzu the terminal potential V te rm.
- Variable impedance element 40 includes a diode 81 and a diode 82 connected in parallel.
- the direction of the current flowing through the diode 81 is opposite to the direction of the current flowing through the diode 82 (forward direction).
- the diode 82 is biased forward when the potential of the transmission line 30 rises to (V term + V f >) due to the output buffer 12 outputting high-level data to the transmission line 30. As a result, the variable impedance The impedance value of the element 40 becomes very low, where V f is the forward voltage of the diodes 81 and 82.
- the diode 81 controls the output buffer 12 to transmit low-level data to the transmission line 30.
- variable impedance element 40 When the potential of the transmission line 30 drops to (V term ⁇ V f ) due to the output, it is forward biased. As a result, the impedance value of the variable impedance element 40 becomes very low.
- FIG. 2 shows the transition of the potential of the transmission line 30 when high-level data and low-level data are alternately output from the driver 10.
- the potential of the transmission line 30 transitions from a high level to a low level (or from a low level to a high level) at a high speed at a constant speed. This is because when the potential of the transmission line 30 is close to the terminal potential V t e fm is the impedance value of the variable impedance element 40 is set to a high value, the transmission line to the output buffer 12 of the driver 10 30 This is because only a load corresponding to the capacity of the above is applied.
- the upper limit of the amplitude of the data transmitted from the dryno 10 is clamped to the potential (V te rm + V f ), and the lower limit of the data amplitude is clamped to the potential ( te rm — V f ). Is done.
- the amplitude of data transmitted from the driver 10 is given range - is limited to (V te rm V f ⁇ V term + V f).
- small amplitude data can be transmitted.
- the diodes 81 and 82 are Schottky diodes
- the forward voltage Vf is about 0.4 V. Therefore, the potential of the data line on the transmission line 30 swings between 1.5 V and 0.7 V with the terminal potential V term of 1.1 V as a median value.
- the potential of the transmission line 30 and the final potential as the reference potential are changed.
- a potential difference between the potential of the transmission line 30 and the terminal potential V term can be sufficiently ensured.
- the logical judgment in the receiver 20 can be reliably performed.
- the resistor 31 connected in series between the variable impedance element 40 and the transmission line 30 provides a current flowing between the terminal potential Vtm and the driver 10 when the diodes 81 and 82 are forward-biased. Used to limit.
- the reference potential VR 13 ⁇ 4 VR 2 of the output buffer 12 of the driver 1 0 potential (V term + V f), the potential - by setting each in the vicinity of the (V t erm V f), terminal potential V te and Doraino It is possible to cut the direct current flowing between the terminal 10.
- the potential of the transmission line 30 becomes the potential (V te rm + V f ) or the potential (V te rm — V f )
- the transistors 71 p and 71 n of the output buffer 12 are turned off, and the output impedance of the driver 10 becomes extremely high. Because it becomes.
- the potential of the transmission line 30 is maintained at the potential (v term + v f ) or the potential (v term _v f ) by the capacitance of the diodes 81 and 82 and the capacitance of the transmission line 30 itself. Therefore, the potential difference required for the logical judgment in the receiver 20 is maintained continuously.
- FIG. 3 shows the change over time in the output impedance of the driver 10 and the impedance value of the variable impedance element 40.
- the output impedance of the driver 10 and the impedance value of the variable impedance element 40 each take one of two values.
- the higher value of the two values is represented as “H”, and the lower value is represented as “L”.
- both the output impedance of the driver 10 and the impedance value of the variable impedance element 40 are set to “Hj” (period T.
- the driver 10 and the variable impedance element DC current flowing between 40 ° C and 40 ° C can be cut.
- the output impedance of the driver 10 is set to “L” (period T 2 ). Thereby, the potential of the transmission line 30 changes at a high speed.
- the output impedance of the dry / 1 0 is set to "H" (the period T 4).
- the transmission line 30 potential is the reference potential! ⁇ Traversal Luke, or, when the potential of the transmission line 30 is lower than the reference potential VR 2, as described above, the transistor 7 1 p, 7 1 n of the output buffer 12 is because both turned off. Accordingly, since the potential of the transmission line 30 is moved Qian toward the terminal potential V te rm, the potential of the transmission line 30 falls below the potential (V te rm + V f) , or the potential (V term - V f ). As a result, impedance of the variable impedance element 40 is set to "Hj (period T 5).
- the driver 1 0 output impedance and the variable impedance element
- Both are set to “H” with the impedance value of 40.
- a DC current flowing between the dryno 10 and the variable impedance cow 40 can be cut.
- the reference potential is set to be equal to the potential (V te rm + V f)
- the reference potential VR 2 is potential - is set to be equal to (V te rm V f)
- the output impedance of the driver 10 changes from “L” to “H” at the same time as the impedance value of the variable impedance element 40 changes from “H” to “L”.
- the impedance value of the variable impedance element 40 and the output impedance of the driver 10 change so as to be related to each other.
- the DC current flowing between the driver 10 and the variable impedance element 40 can be cut, and even if such a DC current is cut, the data on the transmission line 30 can be cut. Can be maintained. This helps reduce power consumption during periods when data does not transition.
- the probability of data transition is about 10% in the case of computer CPU. Therefore, the effect of reducing power consumption during periods when data does not transition is greater than the effect of reducing power consumption during periods when data transitions.
- the current consumed by the conventional data transmission apparatus 200 is as follows. However, it is assumed that the capacitance of the transmission line 230 is 20 pF and the DC current flowing through the terminating resistor 240 is 8 mA.
- FIG. 4D shows the configuration of the data transmission device 1b according to the first embodiment of the present invention.
- the data transmission device 1b includes a variable impedance element 42 having an impedance value variably controllable according to a control signal.
- One terminal 42 a of the variable impedance element 42 is connected to an end of the transmission line 30 on the receiver 20 side.
- the other terminal 42b of the variable impedance element 42 is connected to the terminal potential Vte ⁇ .
- the impedance value of the variable impedance element 42 changes according to the control signal CTL or CTL 2 input from outside the variable impedance element 42.
- the control signal CTI ⁇ is input from the driver 10 to the variable impedance element 42.
- the control signal CTL 2 is input from the receiver 20 to the variable impedance element 42.
- Dryno '10 has an output buffer (DB) 12 that outputs data to transmission line 30.
- the receiver 20 has an input buffer (RB) 22 for receiving data from the transmission line 30.
- the output buffer 12 optimizes high-speed transmission and low power consumption by controlling the variable impedance element 42.
- the output buffer 12 controls the variable impedance element 42 such that the impedance value of the variable impedance element 42 decreases before outputting the data to the transmission line 30.
- the impedance value of the variable impedance element 42 is controlled to match the characteristic impedance of the transmission line 30.
- Such control is performed using the control signal CTI ⁇ . This makes it possible to transmit data at high speed.
- the output buffer 12 controls the variable impedance element 42 so that the impedance value of the variable impedance element 42 becomes high.
- the DC current flowing between the variable impedance element 42 and the driver 10 is suppressed.
- the power consumed by the overnight transmission device 1b is reduced.
- the output impedance of the dryno 10 increases when the impedance value of the variable impedance element 42 is high, and the output impedance of the driver 10 decreases when the impedance value of the variable impedance element 42 is low.
- the force buffer 12 is controlled.
- the input buffer 22 may control the impedance value of the variable impedance element 42.
- the input buffer 22 controls the variable impedance element 42 such that the impedance value of the variable impedance element 42 decreases. Such control is performed by using the control signal CTL 2.
- the input buffer 22 controls the variable impedance element 42 so that the impedance value of the variable impedance element 42 becomes higher.
- the DC current flowing between the variable impedance element 42 and the driver 10 is suppressed. As a result, the power consumed by the data transmission device 1b is reduced.
- the output impedance of the driver 10 increases when the impedance value of the variable impedance element 42 is high, and the output impedance of the driver 10 decreases when the impedance value of the variable impedance element 42 is low.
- the force buffer 12 is controlled. Such control is performed, for example, by supplying a control signal CTL 3 from the input buffer 2 2 to the output buffer 1 2.
- the impedance value of the variable impedance element 42 and the output impedance of the driver 10 are controlled according to whether data is being transmitted or not being transmitted. You.
- the impedance value of the variable impedance element 42 and the output impedance of the driver 10 may be controlled.
- the state in which data is transmitted is further subdivided, and the impedance value of the variable impedance element 42 and the output impedance of the driver 10 are further finely controlled in the state in which data is transmitted. Things.
- FIG. 5A shows the configuration of the variable impedance element 42.
- the variable impedance element 4 2, a resistor R i to R 4 which are connected in series between the terminals 4 2 a and the terminal 4 2 b, provided so as to correspond to the respective resistors 1 ⁇ ⁇ 13 ⁇ 4 4 and a sweep rate Tutsi SW 1 to SW 4 for bypassing, and a SW '1 ⁇ SW' 4.
- Off of switches SW ' ⁇ ⁇ 4 are controlled by a control signal CTL 2.
- the impedance value of the variable impedance element 42 can be changed in four stages.
- the state switch SW SWd are all off, by turning on and off the Suitsuchi SW i ⁇ SW '4 in accordance with the control signal CTL 2, it is possible to change the impedance value of the variable impedance element 42 in four stages.
- FIG. 4B shows a configuration of data transmission device 1c according to Embodiment 1 of the present invention.
- the transmission device l c includes a controller 50 that variably controls the impedance value of the variable impedance element 44.
- the CPU 60 provides the controller 50 with information indicating the operation speed of the CPU 60.
- the information indicating the operation speed of the CPU 60 is, for example, information indicating an operation mode of the CPU 60 (for example, a normal operation mode, a power saving operation mode, and the like).
- the information indicating the operation speed of the CPU 60 may be information indicating the operation clock frequency.
- the controller 50 detects whether the CPU 60 is operating at a high speed or the CPU 60 is operating at a low speed, based on information provided from the CPU 60. '
- the controller 50 When the CPU 60 is operating at a high speed, the controller 50
- variable impedance element 44 Control the variable impedance element 44 so that the impedance value of the dance element 42 becomes low. Such control of the variable impedance element 44 is performed using the control signal C TL 5. By reducing the impedance value of the variable impedance element 44, it is possible to transmit data at high speed.
- the controller 50 adjusts the variable impedance so that the impedance value of the variable impedance element 44 increases.
- Control device 42 Such control of the variable impedance element 44 is performed using the control signal CTL S.
- the DC current flowing between the variable impedance element 44 and the driver 10 is suppressed by increasing the impedance value of the variable impedance element 44. As a result, the power consumed by the overnight transmission device 1c is reduced.
- variable impedance element 44 As described above, by adjusting the impedance value of the variable impedance element 44 according to the operating speed of the CPU 60, it is possible to achieve both high-speed data transmission at a system level and low power consumption.
- the controller 50 controls the output buffer 12 so that the output impedance of the driver 10 is reduced.
- Such control of the output buffer 12 is carried out have use the control signal CTL 4.
- the controller 50 controls the output buffer 12 so that the output impedance of the driver 10 becomes high.
- Such control of the output buffer 12 is performed using the control signal CTL 4.
- the DC current flowing between the variable impedance element 44 and the driver 10 is suppressed by increasing the output impedance of the driver 10. As a result, the power consumed by the data transmission device 1c is reduced. '
- FIG. 5B shows the configuration of the variable impedance element 44.
- the variable impedance element 44 includes resistors R E ⁇ R 4 which are connected in series between the terminal 44 a and the terminal 44 b, the resistor 1 ⁇ ⁇ 13 ⁇ 4_ bypass provided so as to correspond to each of the four And SWi SW.
- FIG. 6 shows the configuration of the output buffer 12a of the driver 10.
- Output buffer 12 (FIG. 1) may be replaced by output buffer 12a.
- the output buffer 12 a is characterized in that it has two sets of transistors having different sizes as push-pull transistors for outputting data to the transmission line 30. That is, the output buffer 12a includes a pair of large PMOS transistors 91p and NMOS transistors 91n and a pair of small PMOS transistors 92p and 92n.
- Predetermined logic determined by the NAND element 73, the NOR element 74, and the operational amplifiers 75 and 76 is input to the gates of the transistors 91p and 9In.
- the operational amplifier 75 receives the potential of the transmission line 30 and the reference potential VRi.
- the op amp 76 is a potential and a reference potential VR 2 and force ⁇ input of the transmission line 30.
- the output of the inverter 78 is input to the gates of the transistors 92 ⁇ and 92 ⁇ . In the evening 78, the data D a ta is input.
- the output buffer 12a When transitioning the data on the transmission line 30, the output buffer 12a turns on one of the transistors 91p and 92p or the transistors 91n and 92n, depending on the value of the data to be transmitted. I do. Thereby, the potential of the transmission line 30 changes at high speed.
- the transistor 9 lp When the potential of the transmission line 30 exceeds the reference potential, the transistor 9 lp is turned off. Transistor 92p remains on. When the potential of the transmission line 30 is less than the reference potential level VR 2, the transistor 91 n is turned off. Transistor 92 ⁇ remains on.
- FIG. 7A shows the configuration of the variable impedance element 46.
- FIG. 7B shows the configuration of the variable impedance element 48.
- the variable impedance element 44 (FIG. 1) can be replaced by variable impedance elements 46,48.
- Variable impedance element 46 includes a resistor 93 connected in series with diodes 81 and 82 connected in parallel. One end of the resistor 93 is connected to the terminating potential V term, and the other end of the resistor 93 is connected to the transmission line 30 via diodes 81 and 82.
- Variable impedance element 48 includes a resistor 94 connected in series with diodes 81 and 82 connected in parallel. One end of the resistor 94 is connected to the terminal potential Vte ⁇ via the diodes 81 and 82, and the other end of the resistor 94 is connected to the transmission line 30.
- variable impedance elements 46, 48 have very high impedance values until one of the diodes 81, 82 is forward biased.
- variable impedance element 46 will have an impedance value substantially equal to the impedance value of resistance 93, and variable impedance element 48 will have a resistance 9 It has a impedance value substantially equal to the impedance value of 4.
- Inpi 1 "Dance value of the diode 81, 82 is variable Inpi one dance 4 6 after being forward biased, 4 8, compared with the impedance value of the variable impedance element 4 4 (FIG. 1) Therefore, it is possible to suppress the peak value of the current flowing to the driver 10 when the diodes 81 and 82 are biased in the forward direction.
- the resistors 93 and 94 have a resistance value equal to the characteristic impedance Z of the transmission line 30. Thus, reflection at the end of the transmission line 30 on the receiver 20 side is suppressed.
- the forward voltage Vf of the diodes 81 and 82 is set to a high level by the driver 10. Substantially coincides with the amplitude value of the potential of the transmission line 30 from the terminal potential V te rm when outputting the Isseki de Le, and an end potential when the driver 10 outputs the data of mouth first level It preferably has a value that substantially matches the amplitude value of the potential of the transmission line 30 from V term .
- the impedance of the transmission line 30 and the impedance of the resistor 93, 94 are both 50 ohms, the terminating potential V te rm is 1. IV, the output impedance of the driver 10 is assumed to be 50 ohms.
- the driver 10 when the driver 10 outputs high-level data, the potential of the transmission line 30 becomes 1.65 V, and when the driver 10 outputs single-level data, The potential becomes 0.55 V.
- the forward voltage V f of the diodes 81 and 82 is preferably set to 0.55 V.
- FIG. 8A shows a configuration of a data transmission device 2a according to the second embodiment of the present invention.
- the transmission device 2a performs so-called differential data transmission.
- the data transmission device 2a includes a driver 110 for transmitting data, a receiver 120 for receiving data transmitted by the dryino 110, and a transmission line 130 for connecting the driver 110 and the receiver 120. , Including 131 and. Positive logic data is transmitted from the driver 110 to the receiver 120 via the transmission line 130. Negative logic data is transmitted from the driver 110 to the receiver 120 via the transmission line 131.
- the data transmission device 2a includes a variable impedance element 140 whose impedance value automatically changes according to the potential of the transmission line 130, and a variable impedance element whose impedance value automatically changes according to the potential of the transmission line 131. 141 is further included.
- the variable impedance element 140 is connected to an end of the transmission line 130 on the receiver 120 side.
- the variable impedance element 141 It is connected to the end of the receiver 120 side.
- Variable impedance element 140 includes diodes 18 1 and 18 2.
- the anode of the diode 181 is connected to the terminal potential V terml via the resistor 191, and the cathode of the diode 181 is connected to the transmission line 130.
- the anode of diode 182 is connected to transmission line 130 and the force source of diode 182 is connected to ground V ss via resistor 192.
- resistors 191 and 192 can be omitted. If the resistor 191 is omitted, the anode of the diode 181 is connected to the termination potential V terml . If the resistor 1922 is omitted, the force source of the diode 182 is connected to ground Vss.
- the variable impedance element 141 includes diodes 183 and 184. Daio - anode de 1 8 3, Ri Contact is connected to the terminal potential V te rm2 through the resistor 1 9 3, diode 1 8 3 forces Sword is connected to the transmission line 1 3 1.
- the anode of diode 184 is connected to transmission line 131, and the force sword of diode 184 is connected to ground V ss via resistor 194.
- resistors 1993 and 194 can be omitted. If the resistor 193 is omitted, the anode of the diode 183 is connected to the terminal potential Vterm2 . If resistor 194 is omitted, the force sword of diode 184 is connected to ground V ss .
- the driver 110 is an output buffer (DB) that outputs data to the transmission line 130.
- DB output buffer
- the output buffer 112 is connected to the transmission line 130 via the node 114.
- the output buffer 113 is connected to the transmission line 131 through the node 115.
- the receiver 120 has an input buffer 122 for receiving data from the transmission line 130 and the transmission line 131.
- the input buffer 122 is, for example, a two-input buffer. ⁇ It is an amplifier.
- One input of the input buffer 122 is connected to a transmission line 130 via a pad 124 and a stub resistor 132.
- the other input of the input buffer 122 is connected to the transmission line 13 1 via the pad 125 and the stub resistor 133.
- the variable impedance element 1 4 0 is adjusted so that the condition that the sum of the forward voltages V f of the diodes 18 1 and 18 2 is larger than the potential difference between the terminal potential V termm and the ground V ss is satisfied. Is designed.
- the variable impedance element 14 1 is designed so that the condition that the sum of the forward voltages V f of the diodes 18 3 and 184 is larger than the potential difference between the termination potential V te rm2 and the ground V ss is satisfied. .
- the terminal potentials V terml and V ter rm2 are 1.5 V and the forward voltage V f of the diodes 181-184 is 1.0 V, the above condition is satisfied. .
- FIG. 8B shows the impedance characteristics of the diodes 181-184.
- V te rml the potential V te rm2.
- variable impedance element 140 has a very high impedance value. Data transitions at a high speed at a constant speed.
- the characteristic of the diode 18 is in the low impedance region (see FIG. 8B).
- the potential of the transmission line 130 is lower than the potential (V telml — V f )
- the characteristic of the diode 18 1 is in the low impedance region (see FIG. 8B).
- the diode 181 , 182 are always in the low impedance region.
- variable impedance element 140 will have a very low impedance value for terminal potential V te rml or ground V ss. This is because diode 181 or 182 is forward biased. As a result, the potential (Hi potential) indicating that the data on the transmission line 130 is at a high level is clamped near the potential (V ss + V f ), and the data on the transmission line 130 is at a low level. Potential (Lo potential) is clamped near the potential (V telml — V f ). This limits the data amplitude.
- the Hi potential and the Lo potential of the transmission line 130 are determined by the resistors 191 and 192 and the output impedance of the output buffer 112. For example, by adjusting the output impedance of the output buffer 112, the Hi potential and the Lo potential of the transmission line 130 can be set to 1.0 and 0.5 V, respectively.
- the impedance value of the variable impedance element 140 changes according to the potential of the transmission line 130.
- the impedance value of the variable impedance element 141 changes according to the potential of the transmission line 131.
- the resistance values of the resistors 191 to 194 are equal to the characteristic impedance of the transmission lines 130 and 131.
- the output of the output buffer 112 is returned.
- the DC current consumed by the driver 110 can be significantly reduced.
- the output buffer 1 By increasing the output impedance of 13, the DC current consumed by driver 110 can be significantly reduced.
- FIG. 9 shows a configuration of a data transmission device 2b according to the second embodiment of the present invention.
- the overnight transmission device 2b performs so-called differential data transmission.
- the data transfer device 2b includes a variable impedance element 142.
- One end 142 a of the variable impedance element 142 is connected to the transmission line 130.
- the other end 142 b of the variable impedance element 142 is connected to the transmission line 131.
- the variable impedance element 142 is composed of diodes 185 and 18 connected in parallel.
- variable impedance element 142 Includes 6 and resistor 195.
- the configuration of the variable impedance element 142 is the same as the configuration of the variable impedance element 46 shown in FIG. 7A.
- Variable impedance element 142 may be replaced by variable impedance element 40 (FIG. 1) or variable impedance element 48 (FIG. 7B).
- the output buffers 112 and 113 are configured to monitor both the potential of the transmission line 130 and the potential of the transmission line 131. Setting a potential difference after exceeding the forward voltage V f of Daio one de 185, 186, the output buffer 1 12, 1 13 Cain peak one dance out of high between the potential of the transmission line 131 of the transmission line 130 Is done. 'This makes it possible to significantly reduce the DC current consumed by the driver 110.
- Embodiments 1 and 2 have described data transmission (so-called point-to-point data transmission) when a driver and a receiver are associated one-to-one.
- the application of the present invention is not limited to point-to-point data transmission.
- the present invention can be applied to a data transmission device in which data is transmitted from one driver to a plurality of receivers via a transmission line.
- the variable impedance element described above should be provided at the end of the transmission line. You can do it.
- power consumption can be reduced by suppressing the DC current flowing through the transmission line.
- occurrence of skew can be suppressed. This makes it possible to transmit data at high speed.
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/486,868 US6323756B1 (en) | 1997-09-02 | 1998-01-09 | Data transmitter |
DE69837886T DE69837886T2 (de) | 1997-09-02 | 1998-09-01 | Datensender |
CA002302939A CA2302939C (en) | 1997-09-02 | 1998-09-01 | Variable impedance data transmission device |
EP98940651A EP1014584B1 (en) | 1997-09-02 | 1998-09-01 | Data transmitter |
JP2000509156A JP3498843B2 (ja) | 1997-09-02 | 1998-09-01 | データ伝送装置 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP9/236782 | 1997-09-02 | ||
JP23678297 | 1997-09-02 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1999012262A1 true WO1999012262A1 (fr) | 1999-03-11 |
Family
ID=17005721
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP1998/003896 WO1999012262A1 (fr) | 1997-09-02 | 1998-09-01 | Emetteur de donnees |
Country Status (7)
Country | Link |
---|---|
US (1) | US6323756B1 (ja) |
EP (1) | EP1014584B1 (ja) |
JP (1) | JP3498843B2 (ja) |
KR (1) | KR100389222B1 (ja) |
CA (1) | CA2302939C (ja) |
DE (1) | DE69837886T2 (ja) |
WO (1) | WO1999012262A1 (ja) |
Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
TWI221377B (en) * | 2001-03-16 | 2004-09-21 | Via Tech Inc | Data transmission circuit and related method |
US6483354B1 (en) * | 2001-08-24 | 2002-11-19 | Lsi Logic Corporation | PCI-X driver control |
DE10142410A1 (de) * | 2001-08-31 | 2003-04-03 | Bosch Gmbh Robert | Versorgungsleitungsstruktur zur Energieversorgung von elektrischen Komponenten eines Kraftfahrzeugs |
JP3587814B2 (ja) * | 2001-11-28 | 2004-11-10 | ローム株式会社 | データ伝送システム及びケーブル |
US7093041B2 (en) * | 2001-12-20 | 2006-08-15 | Lsi Logic Corporation | Dual purpose PCI-X DDR configurable terminator/driver |
GB0208014D0 (en) * | 2002-04-05 | 2002-05-15 | Acuid Corp Ltd | Line termination incorporating compensation for device and package parasites |
KR100930789B1 (ko) | 2003-04-29 | 2009-12-09 | 매그나칩 반도체 유한회사 | 출력 드라이버의 출력신호 레벨을 가변할 수 있는 반도체장치 |
KR100666177B1 (ko) * | 2005-09-30 | 2007-01-09 | 삼성전자주식회사 | 모드 레지스터 셋트를 이용하여 초기강화 드라이버의 임피던스 및 강도를 제어하는 출력 드라이버 |
KR101158410B1 (ko) | 2010-10-29 | 2012-06-22 | (주) 코콤 | 음성 라인을 이용한 디지털 데이터 통신 시스템, 디지털 데이터 송신 장치 및 디지털 데이터 수신 장치 |
JPWO2012114392A1 (ja) * | 2011-02-25 | 2014-07-07 | パナソニック株式会社 | 入力保護回路 |
US8766674B1 (en) * | 2013-03-15 | 2014-07-01 | Qualcomm Incorporated | Current-mode buffer with output swing detector for high frequency clock interconnect |
US9548734B1 (en) * | 2015-12-26 | 2017-01-17 | Intel Corporation | Smart impedance matching for high-speed I/O |
Citations (2)
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JPS63131436U (ja) * | 1987-02-20 | 1988-08-29 | ||
JPH04315335A (ja) * | 1991-04-15 | 1992-11-06 | Matsushita Electric Works Ltd | 多重伝送システム |
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US3657478A (en) | 1969-12-30 | 1972-04-18 | Honeywell Inc | Interconnection bus system |
US4450370A (en) | 1979-01-31 | 1984-05-22 | Phillips Petroleum Company | Active termination for a transmission line |
US4623871A (en) * | 1984-06-04 | 1986-11-18 | Yamatake Honeywell | Receiving apparatus |
JPS62136145A (ja) | 1985-12-09 | 1987-06-19 | Fuji Facom Corp | 1:nデ−タ伝送方式 |
JPS63131436A (ja) | 1986-11-20 | 1988-06-03 | Fujitsu General Ltd | プラズマデイスプレイパネルの駆動装置 |
KR100225594B1 (ko) | 1991-03-29 | 1999-10-15 | 가나이 쯔도무 | 반도체 집적회로장치에서 실행되는 전류구동신호 인터페이스 |
JPH0667772A (ja) | 1992-08-14 | 1994-03-11 | Ricoh Co Ltd | データ伝送装置 |
US5398025A (en) * | 1992-11-10 | 1995-03-14 | Modicon, Inc. | Input module |
US5635896A (en) * | 1993-12-27 | 1997-06-03 | Honeywell Inc. | Locally powered control system having a remote sensing unit with a two wire connection |
JPH07221624A (ja) | 1994-02-04 | 1995-08-18 | Hitachi Ltd | 入出力インタフェース回路装置 |
US5604450A (en) | 1995-07-27 | 1997-02-18 | Intel Corporation | High speed bidirectional signaling scheme |
KR0167294B1 (ko) | 1995-12-16 | 1999-01-15 | 문정환 | 순차엑세스를 위한 메모리장치 |
US6150922A (en) * | 1997-01-23 | 2000-11-21 | Lucent Technologies Inc. | Serial communication technique |
US5952914A (en) * | 1997-09-10 | 1999-09-14 | At&T Corp. | Power line communication systems |
US6154488A (en) * | 1997-09-23 | 2000-11-28 | Hunt Technologies, Inc. | Low frequency bilateral communication over distributed power lines |
-
1998
- 1998-01-09 US US09/486,868 patent/US6323756B1/en not_active Expired - Lifetime
- 1998-09-01 DE DE69837886T patent/DE69837886T2/de not_active Expired - Lifetime
- 1998-09-01 WO PCT/JP1998/003896 patent/WO1999012262A1/ja active IP Right Grant
- 1998-09-01 KR KR10-2000-7002222A patent/KR100389222B1/ko not_active IP Right Cessation
- 1998-09-01 CA CA002302939A patent/CA2302939C/en not_active Expired - Fee Related
- 1998-09-01 EP EP98940651A patent/EP1014584B1/en not_active Expired - Lifetime
- 1998-09-01 JP JP2000509156A patent/JP3498843B2/ja not_active Expired - Fee Related
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
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JPS63131436U (ja) * | 1987-02-20 | 1988-08-29 | ||
JPH04315335A (ja) * | 1991-04-15 | 1992-11-06 | Matsushita Electric Works Ltd | 多重伝送システム |
Non-Patent Citations (1)
Title |
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See also references of EP1014584A4 * |
Also Published As
Publication number | Publication date |
---|---|
EP1014584A4 (en) | 2001-02-07 |
JP3498843B2 (ja) | 2004-02-23 |
EP1014584A1 (en) | 2000-06-28 |
KR100389222B1 (ko) | 2003-06-27 |
EP1014584B1 (en) | 2007-06-06 |
CA2302939C (en) | 2003-11-18 |
KR20010023574A (ko) | 2001-03-26 |
DE69837886D1 (de) | 2007-07-19 |
CA2302939A1 (en) | 1999-03-11 |
DE69837886T2 (de) | 2008-02-14 |
US6323756B1 (en) | 2001-11-27 |
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