JP2012217081A - Adaptive reception system, adaptive transmission/reception system, and plural channel transmission/reception system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten a jitter tolerance by stabilizing adjustment of a phase of a sampling clock near a lock point and control of an equalizer part.SOLUTION: A phase comparison part outputs a phase comparison signal LAG(n) indicating whether an edge of an equalization signal EQDATA exists in a first section between a sampling timing and a timing before the sampling timing by a predetermined first phase, and outputs a phase comparison signal LEAD(n) indicating whether an edge of the equalization signal EQDATA exists in a second section between the sampling timing and a timing after the sampling timing by a predetermined second phase. A determination part compares an output pattern of the phase comparison signals LAG(n), LEAD(n) corresponding to each bit of a detection data pattern with a predetermined comparison object pattern, and determine whether one bit of the equalization signal EQDATA is longer or shorter than one cycle of a sampling clock CK based on whether the output pattern is matched with the comparison object pattern.

Description

  The present invention relates to an adaptive reception system that receives a transmission signal output from an adaptive transmission system as a reception signal via a differential transmission path, an adaptive transmission / reception system including the adaptive reception system, and the adaptive transmission / reception. The present invention relates to a multi-channel transmission / reception system including a plurality of systems.

  Patent Document 1 discloses a receiver including an equalizer that receives a digital signal from a transmitter and changes a frequency characteristic, and a receiver logic that adjusts the gain of the equalizer. In this receiver, the receiver logic generates a data value by sampling the equalizer output at a certain data point, and generates a boundary value by sampling the equalizer output at a certain data boundary point, The gain of the equalizer is adjusted based on the generated data value and boundary value.

  Patent Document 2 discloses a clock data restoration device that restores a clock signal based on an input digital signal. This clock data restoration device includes an equalizer unit, a sampler unit, a clock generation unit, and an equalizer control unit. The equalizer unit adjusts the level of the input digital signal and outputs the adjusted digital signal. The sampler unit samples the digital signal output from the equalizer unit with a clock CKX indicating the transition timing of data bits to obtain a value DX (n), and a clock indicating the central time of each bit period Sampling with CK is performed to obtain a value D (n). Further, the clock generation unit sets the phase of the clock CKX and the clock CK to “D (n−1) ≠ DX (n−1) = D (n)” as shown in FIG. UP signal (phase comparison signal) that becomes a significant value when is established, and a significant value when “D (n−1) = DX (n−1) ≠ D (n)” is established. Is adjusted based on the DN signal (phase comparison signal). The equalizer control unit controls an offset voltage value added to the input digital signal by the equalizer unit based on the value D (n) and the value DX (n).

  Patent Document 3 discloses a clock data recovery circuit that compares the phases of input data and a sampling clock and generates a sampling clock according to the comparison result, and the edge of the sampling clock is separated from the edge of the input data by a predetermined interval or more. As described above, the sampling clock phase is changed.

  Patent Document 4 discloses a transfer device in which a transmission-side LSI and a reception-side LSI are connected by a differential transmission path. The transmission-side LSI includes a pre-emphasis circuit and a pseudo-random pattern generator that generates a pseudo-random pattern according to a predetermined algorithm. On the other hand, the receiving side LSI compares the pseudo random number pattern generated by the input buffer amplifier and the pseudo random number pattern generator of the transmitting side LSI with the expected value pattern generated by the same algorithm as the pseudo random number pattern generator. And a pseudo-random pattern comparator. Based on the comparison result by the pseudo random number pattern comparator, the pre-emphasis amount of the pre-emphasis circuit of the transmission side LSI and the offset amount of the input buffer amplifier of the reception side LSI are adjusted.

JP 2008-22537 A JP 2008-99017 A JP 2004-180188 A JP 2008-22392A

  However, in Patent Document 2, since the phase comparison signal is constantly output even near the lock point, the adjustment of the sampling clock phase near the lock point and the adaptive control operation of the equalizer are both unstable, and jitter tolerance. Becomes lower. Further, since the adjustment of the phase of the sampling clock and the control of the offset voltage value added to the input digital signal by the equalizer unit are both performed based on the value D (n) and the value DX (n), sampling is performed. There is a possibility that the adjustment of the clock phase and the control of the offset voltage value interfere with each other, and each of them is erroneously locked.

  Further, Patent Document 1 does not describe a method of generating a clock used for sampling the output of the equalizer.

  Moreover, in the said patent document 3, since the equalizer is not mounted, the influence of ISI (Inter-Symbol Interference) cannot be reduced. The speed cannot be increased unless the stability of both the adjustment of the phase of the sampling clock and the adaptive control of the equalizer is improved.

  In Patent Document 4, not only the offset amount of the input buffer amplifier of the reception side LSI but also the pre-emphasis amount of the pre-emphasis circuit of the transmission side LSI is adjusted. Therefore, even when the signal attenuation of the differential transmission path is large Signal transmission. However, in order to optimize the pre-emphasis amount, it is necessary to provide time for training with a pseudo-random pattern. In addition, after normal transmission is started using the pre-emphasis amount obtained by training, an environmental change such as a temperature change or EMI (Electro Magnetic Interference) may occur in the differential transmission path. In such a case, in order to adapt the pre-emphasis amount to the changed environment, it is necessary to interrupt normal transmission and perform training again.

  The present invention has been made in view of such a point, and an object of the present invention is to stabilize the adjustment of the phase of the sampling clock near the lock point and the control of the equalizer section, and to increase the jitter tolerance. . It is another object of the present invention to optimize the amount of pre-emphasis without training with a pseudo-random pattern.

  In order to solve the above problem, an adaptive reception system according to an aspect of the present invention receives a transmission signal output by an adaptive transmission system as a reception signal via a differential transmission path, and the transmission signal is An adaptive reception system obtained by performing pre-emphasis on a logical signal by an adaptive transmission system, wherein the received signal is equalized based on an intensity adjustment signal indicating equalization intensity, and an equalized signal Based on a sampling clock and a first clock advanced by a first predetermined phase from the sampling clock, a sampling timing and a timing before the first predetermined phase from the sampling timing, And outputting a first phase comparison signal indicating whether or not an edge of the equalized signal exists in the first interval between Based on the sampling clock and the second clock delayed by a second predetermined phase from the sampling clock, the second interval between the sampling timing and the timing after the second predetermined phase from the sampling timing, A second phase comparison signal indicating whether or not an edge of the equalization signal exists is output, and the first interval and the second interval are in a state where the phases of the equalization signal and the sampling clock coincide with each other. Based on the phase comparison unit set so as not to include the edge of the equalization signal and the first and second phase comparison signals, so that the phases of the equalization signal and the sampling clock match. A clock adjusting unit for adjusting and outputting the phase of the sampling clock; and a sample by the sampling clock for the equalization signal. A pattern detection unit for detecting a detection data pattern of 3 or more consecutive bits including at least two bit inversions from a restoration signal obtained by performing the processing, and each bit of the detection data pattern detected by the pattern detection unit The output pattern of the first and second phase comparison signals corresponding to 1 is compared with a predetermined comparison target pattern, and the bit time width of the equalization signal is longer or shorter than 1 UI based on whether or not they match. A determination unit that determines whether or not, an adaptive control filter unit that adjusts the intensity adjustment signal based on a determination result by the determination unit, and an equalization intensity indicated by the intensity adjustment signal is equal to or greater than a preset upper threshold value In some cases, a first control for outputting a control signal requesting to increase the strength of the pre-emphasis to the adaptive transmission system, and the strength adjustment. A second control for outputting, to the adaptive transmission system, a control signal requesting to lower the pre-emphasis strength when the equalization strength indicated by the node signal is equal to or lower than a preset lower threshold value; A pre-emphasis control unit that executes at least one of the above is provided.

  According to this aspect, the first and second phase comparison signals are generated based on whether or not the edge of the equalization signal exists in the first and second sections before and after the sampling timing. Therefore, the values of the first and second phase comparison signals are stabilized in a state where the phases of the equalization signal and the sampling clock match, that is, near the lock point, and the sampling clock phase is not adjusted. Therefore, the tolerance for high frequency noise is kept high, and stable adaptive operation of the equalizer is possible. Further, interference between the adjustment of the phase of the sampling clock and the control of the equalization intensity can be suppressed.

  If the detection data pattern is included in the restoration signal, the phase of the sampling clock, the equalization intensity of the equalizer unit, and the intensity of pre-emphasis can be adjusted.

  A first control for outputting to the adaptive transmission system a control signal requesting to increase the pre-emphasis strength when the equalization strength indicated by the strength adjustment signal is equal to or greater than a preset upper threshold; Second control for outputting a control signal requesting to lower the pre-emphasis strength to the adaptive transmission system when the equalization strength indicated by the strength adjustment signal is equal to or lower than a preset lower threshold. At least one of is executed. This allows the adaptive transmission system to adjust the strength of pre-emphasis even when the signal attenuation in the differential transmission line is large and stabilization is not possible within the adjustable range of the equivalent strength of the equalizer unit alone. As a result, the equalization signal can have an appropriate strength and signal transmission can be stabilized. Therefore, it is possible to obtain an equalized signal having an appropriate intensity with a wider control range than when the equalizing intensity is adjusted by the equalizer section alone.

  According to the present invention, tolerance against high-frequency noise is kept high, and stable adaptive operation of the equalizer becomes possible. Further, interference between the adjustment of the phase of the sampling clock and the control of the equalization intensity can be suppressed.

  In addition, if the detection data pattern is included in the restoration signal, it is possible to adjust the sampling clock phase, the equalization strength of the equalizer unit, and the pre-emphasis strength by detecting the detection data pattern from the restoration signal. Therefore, it is not necessary to provide time for training with a pseudo-random pattern. In addition, even if an environmental change such as temperature change or EMI occurs in the differential transmission path after starting reception of the received signal, if the detected data pattern is detected from the restored signal, the sampling clock is not interrupted. , The equalizer equalization intensity, and the pre-emphasis intensity can be adapted to the environment after the change.

  Furthermore, an equalized signal having an appropriate intensity can be obtained with a wider control range than when the equalizing intensity is adjusted by the equalizer section alone.

It is a block diagram which shows the structure of the adaptive transmission / reception system which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the pre-emphasis part which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the adaptive reception system which concerns on Embodiment 1 of this invention. (A) is a circuit diagram which shows the structure of the equalizer part which concerns on Embodiment 1 of this invention. (B) is a graph which shows the relationship between the frequency of the equalizer part which concerns on Embodiment 1 of this invention, and equalizer intensity | strength (equalization intensity | strength). 6 is a timing chart illustrating a phase comparison operation of the clock data recovery unit according to the first embodiment of the present invention. It is a block diagram which shows the structure of the adaptive control part which concerns on Embodiment 1 of this invention. It is a timing chart which shows an equalization signal, a decompression | restoration signal, etc. in case the transmission waveform which concerns on Embodiment 1 of this invention contains the isolated bit whose time width is just 1 UI (Unit Interval). It is explanatory drawing explaining the determination algorithm of the time width of the isolated bit which concerns on Embodiment 1 of this invention. It is explanatory drawing explaining the determination algorithm of the time width of the isolated bit which concerns on Embodiment 1 of this invention. It is a state transition diagram which shows the state transition of the filter part for adaptive control which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the intensity | strength adjustment signal represented by the Gray code based on Embodiment 1 of this invention. (A) is explanatory drawing which shows the flow of the signal at the time of transfer of the control signal CTRDT in the adaptive transmission / reception system 1 which concerns on Embodiment 1 of this invention. (B) is an explanatory diagram showing a signal flow when the control signal CTRDT is transferred when the adaptive transmission system 20 does not support pre-emphasis intensity adjustment. It is a block diagram which shows the structure of the adaptive control part which concerns on the modification 2 of Embodiment 1 of this invention. It is explanatory drawing which shows the detection data sequence detected by the pattern detection part which concerns on the modification 2 of Embodiment 1 of this invention, and the filter stage number corresponding to each detection data sequence. It is a block diagram which shows the structure of the multiple channel transmission / reception system which concerns on Embodiment 2 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, components having functions similar to those of the other embodiments are denoted by the same reference numerals and description thereof is omitted.

Embodiment 1
FIG. 1 shows an adaptive transmission / reception system 1 according to Embodiment 1 of the present invention. The adaptive transmission / reception system 1 includes an adaptive transmission system 20 and an adaptive reception system 10, and a differential transmission path 30 and a control bus 40 connected therebetween.

  The adaptive transmission system 20 includes a TX logic 21, a TX control unit 22, a pre-emphasis unit 23, and a TX driver 24.

  The TX logic 21 generates a logic signal LGDATA.

  The TX control unit 22 outputs a pre-emphasis intensity adjustment signal EMPADJ according to the control signal CTRDT input from the adaptive reception system 10 via the control bus 40.

  The pre-emphasis unit 23 performs pre-emphasis on the logic signal LGDATA generated by the TX logic 21 to obtain a transmission signal TXOUT. The pre-emphasis by the pre-emphasis unit 23 is performed with an intensity corresponding to the intensity adjustment signal EMPADJ output from the TX control unit 22.

  Specifically, as shown in FIG. 2, the pre-emphasis unit 23 includes an amplifier 231, a delay element 232a, an amplifier 232, and an adder 233.

  The amplifier 231 amplifies the logic signal LGDATA generated by the TX logic 21.

  The delay element 232a delays and outputs the logic signal LGDATA by one period of the sampling clock.

  The amplifier 232 amplifies the output of the delay element 232a, that is, the logic signal LGDATA one bit before the logic signal LGDATA amplified by the amplifier 231.

  The amplification factors of the amplifier 231 and the amplifier 232 are variable, and are switched according to the intensity adjustment signal EMPADJ output by the TX control unit 22.

  The adder 233 adds the output of the amplifier 231 and the output of the amplifier 232 and outputs the result.

  Note that immediately after the connection between the adaptive reception system 10 and the adaptive transmission system 20, that is, immediately after the reception of the reception signal RXDATA by the adaptive reception system 10, the pre-emphasis intensity set by the intensity adjustment signal EMPADJ is the adaptive type. This is an intermediate value between the highest value and the lowest value in the intensity range that can be set by the pre-emphasis unit 23 of the transmission system 20.

  In this embodiment, the number of mounted amplifiers is two, but the number of mounted amplifiers may be one or three or more. Further, the configuration of the pre-emphasis unit 23 is not limited to the example of FIG. 2, and may be other configurations as long as the pre-emphasis intensity can be adjusted.

  The TX driver 24 outputs the transmission signal TXOUT obtained by the pre-emphasis unit 23 to the differential transmission path 30.

  FIG. 3 shows the adaptive receiving system 10. The adaptive receiving system 10 includes an equalizer unit 11, a clock data recovery unit 12, an adaptive control unit 13, and a pre-emphasis control unit 16. The equalizer unit 11 receives the reception signal RXDATA that has passed through the differential transmission path 30 and is distorted, performs waveform equalization, and outputs an equalization signal EQDATA. The clock data recovery unit 12 extracts a clock from the equalized signal EQDATA output from the equalizer unit 11, and obtains a restoration signal RDOUT by sampling using the extracted clock.

  FIG. 4A shows the equalizer unit 11. The equalizer unit 11 includes a pair of nMOS transistors 11a and 11b, a resistor 11c connected between the sources of the nMOS transistors 11a and 11b, a capacitor 11d connected between the sources of the nMOS transistors 11a and 11b, and the nMOS transistor. A current source 11e for supplying current to 11a, a current source 11f for supplying current to the nMOS transistor 11b, a resistor 11g connected in series to the drain side of the nMOS transistor 11a, and a drain side of the nMOS transistor 11b in series. And a connected resistor 11h.

  The resistance value of the resistor 11c is adjusted by the intensity adjustment signal EQADJ. The DC gain can be adjusted by adjusting the resistance value of the resistor 11c with the intensity adjustment signal EQADJ. When the DC gain is decreased by increasing the resistance value of the resistor 11c, the high frequency gain is relatively increased with respect to the DC gain. On the other hand, when the DC gain is increased by decreasing the resistance value of the resistor 11c, the DC gain is increased. On the other hand, the high frequency gain is relatively low. Therefore, the equalization intensity can be adjusted by adjusting the resistance value of the resistor 11c by the intensity adjustment signal EQADJ. FIG. 4B shows the relationship between frequency and equalizer strength (equalization strength). The intensity adjustment signal EQADJ may be a continuous signal or a discrete signal. Note that an equalizer having another configuration may be used as the equalizer unit 11. For example, a circuit in which the equalizer units 11 shown in FIG. 4A are connected in multiple stages, or a discrete equalizer such as FFE (Feed-Forward Equalizer) or DFE (Decision Feedback Equalizer) may be used as the equalizer unit 11.

  The clock data recovery unit 12 includes a phase comparison unit 101 and a clock adjustment unit 102.

  The phase comparison unit 101 compares the phase difference between the edge of the equalization signal EQDATA and the edge of the sampling clock CK, and outputs a first phase comparison signal LAG and a second phase comparison signal LEAD.

  Based on the first phase comparison signal LAG and the second phase comparison signal LEAD, the clock adjustment unit 102 applies the sampling clock CK and the first clock CKLAG and the second clock CKLEAD that define the phase comparison window. , Adjust the phase and output. The adjustment of the phase is performed so that the phases of the equalization signal EQDATA and the sampling clock CK are matched.

  FIG. 5 shows the phase comparison operation of the clock data recovery unit 12. The phase comparison unit 101 of the clock data recovery unit 12 outputs a phase comparison signal when an edge of the equalization signal EQDATA exists in the phase comparison window defined by the first clock CKLAG and the second clock CKLEAD. Specifically, the phase comparison unit 101 equalizes between the first interval defined by the first clock CKLAG and the sampling clock CK, that is, between the rising edge of the first clock CKLAG and the rising edge of the sampling clock CK. When the edge of the signal EQDATA exists, the first phase comparison signal LAG for delaying the phases of the first clock CKLAG, the sampling clock CK, and the second clock CKLEAD is output. In addition, the phase comparison unit 101 equalizes the equalization signal between the second interval defined by the sampling clock CK and the second clock CKLEEAD, that is, between the rising edge of the sampling clock CK and the rising edge of the second clock CKLEEAD. When an edge of EQDATA exists, a second phase comparison signal LEAD for advancing the phases of the first clock CKLAG, the sampling clock CK, and the second clock CKLEAD is output. The first interval and the second interval are set so as not to include the edge of the equalization signal EQDATA in a state where the phases of the equalization signal EQDATA and the sampling clock CK coincide with each other. For example, the period of the sampling clock CK, that is, 1 UI It is set to 1/3 or less.

  Further, the phase comparison unit 101 of the clock data recovery unit 12 obtains the restoration signal RDOUT by sampling the equalization signal EQDATA with the sampling clock CK.

  The adaptive control unit 13 receives the restoration signal RDOUT obtained by the phase comparison unit 101, the first phase comparison signal LAG, and the second phase comparison signal LEAD, and determines the equalization state of the equalizer unit 11. . The adaptive control unit 13 performs the first phase comparison signal LAG in the phase comparison section existing immediately before and immediately after the rising edge of the corresponding sampling clock CK for each bit of the continuous at least 3-bit restoration signal RDOUT, and It is determined whether or not each of the second phase comparison signals LEAD is activated. Then, the time width of 1 bit is estimated by comparing the discrimination result with a predetermined output pattern. The adaptive control unit 13 adjusts the strength adjustment signal EQADJ so as to lower the equalization strength when the estimated 1-bit time width is larger than 1 UI, while the estimated 1-bit time width is smaller than 1 UI. Adjusts the intensity adjustment signal EQADJ to increase the equalization intensity. Even when the phase comparison window is limited to a predetermined range and there is an interval in which phase comparison is not performed, the restoration signal RDOUT and the first phase comparison signal LAG are provided for each bit of at least three consecutive restoration signals RDOUT. By referring to the second phase comparison signal LEAD, it is possible to estimate the time width of 1 bit. Further, since the phase comparison window is limited, the edges of the equalization signal EQDATA are concentrated outside the phase comparison window at the time of locking, and the phase comparison signal is not activated. Therefore, it is possible to remove ISI with an optimum equalization strength, to ensure stability at the lock point, and to increase tolerance against high frequency noise.

  Here, a detailed configuration and operation of the adaptive control unit 13 will be described. As shown in FIG. 6, the adaptive control unit 13 includes a pattern detection unit 103, a determination unit 104, and an adaptive control filter unit 105.

  The pattern detection unit 103 outputs an activated detection flag signal PTFRG when detecting a predetermined detection data pattern from the restoration signal RDOUT. The detected data pattern is a pattern in which 010 is followed by a k-bit continuous 0 and a pattern in which a k-bit continuous 1 is followed by 101. Here, k is an integer of 0 or more. The magnitude of distortion due to ISI is highly dependent on the incoming pattern. As shown in FIG. 7, when the same data arrives several times in succession, inverted 1-bit data arrives and further inverted data arrives, for example, when the data pattern is 0010 or 11101, ISI The effect of is strongly generated.

  When the transmission waveform TXOUT of data output from the transmission side includes an isolated bit having a time width of exactly 1 UI, for example, as shown in FIG. 7, the time width of the isolated bit of data RXDATA received at the reception side is differential. Attenuation is caused by passing through the transmission line 30, and becomes smaller than 1 UI. The equalizer unit 11 attempts to equalize the waveform in which distortion caused by such ISI is made as close as possible to the transmission waveform TXOUT. However, in the under-boost state where the equalization strength is weak, the time width of the isolated bit is smaller than 1 UI. It remains. On the other hand, in the overboost state where the equalization strength is strong, after the edge of the isolated bit is emphasized, the data is inverted before the amplitude is stabilized, so that the time width of the isolated bit is larger than 1 UI. . In this way, when the same data arrives multiple times in succession, the inverted 1-bit data arrives, and when the inverted data arrives, the current equalization is detected by detecting the time width of the isolated bits. Whether the state is an under boost state or an over boost state can be determined. Therefore, the pattern detection unit 103 differs between the restoration signal RDOUT sampled at time t = (n−1) T (where n is an integer equal to or greater than 1) and the restoration signal RDOUT sampled at time t = nT. It is detected that the restored signal RDOUT sampled at t = nT is different from the restored signal RDOUT sampled at time t = (n + 1) T, and the restored signal RDOUT sampled at time t = (n−1) T. Is detected to be equal to the restoration signal RDOUT obtained from k consecutive samples before time t = (n−1) T (becomes a low frequency signal), the detection flag activated. Signal PTFRG is output to determination unit 104.

  The determination unit 104 determines whether the time width of the isolated bit is longer or shorter than 1 UI based on the restoration signal RDOUT, the first phase comparison signal LAG, and the second phase comparison signal LEAD. Outputs an activated first adjustment signal EQADJ-DN in order to reduce the equalization strength of the equalizer section 11. On the other hand, when the time width of the isolated bit is shorter than 1 UI, the activated second adjustment signal EQADJ-UP is output to increase the equalization strength of the equalizer unit 11. In this embodiment, the phase comparison window is limited to a certain range and does not use a clock for discriminating the boundary point between data. Therefore, it is impossible to determine the time width of the isolated bit with reference to the sampling data at the boundary point. However, the first comparison is made in the phase comparison window immediately before and immediately after the sampling clock CK corresponding to each bit of the restored signal RDOUT and the continuous restored signal RDOUT of at least 3 bits including isolated bits (inversion of two locations). The time width of the isolated bit can be determined by analyzing the active states of the phase comparison signal LAG and the second phase comparison signal LEAD.

  8 and 9 show an algorithm for determining the time width of isolated bits. FIG. 8 shows an algorithm for determining that the time width of an isolated bit is 1 UI or more, and FIG. 9 shows an algorithm for determining that the time width of an isolated bit is 1 UI or less.

  8 and 9, a phase comparison window (n−1), a phase comparison window (n), and a phase comparison window (n + 1) are three successive phase comparison windows, LAG (n−1) / LEAD. (N−1), LAG (n) / LEAD (n), LAG (n + 1) / LEAD (n + 1) are activated when the edge of the equalization signal EQDATA exists in each phase comparison window. And a second phase comparison signal. When the data sampled by CK (n−1) is different from the data sampled by CK (n), and the data sampled by CK (n) is different from the data sampled by CK (n + 1), That is, when the data pattern includes a data string of 010 or 101, it is possible to determine the time width of the isolated bit.

  Under such conditions, when EQDATA (pattern 1), EQDATA (pattern 2), and EQDATA (pattern 3) in FIG. 8 arrive, it is determined that the time width of the isolated bit exceeds 1 UI. Whether the time width of the isolated bit is 1 UI or more depends on whether the first phase comparison signal LAG (n) and the second phase comparison signal LEAD (n) are both inactive in the phase comparison window (n). And / or at least one of the second phase comparison signal LEAD (n−1) of the phase comparison window (n−1) and the first phase comparison signal LAG (n + 1) of the phase comparison window (n + 1). It can be determined based on whether or not the condition that is activated is satisfied. If both of these conditions are satisfied, it is determined that the time width of the isolated bit exceeds 1 UI, and the first adjustment signal EQADJ-DN is activated, while one or both of these conditions are satisfied. If not satisfied, it is determined that the time width of the isolated bit does not exceed 1 UI, and the first adjustment signal EQADJ-DN is not activated.

  In addition, when EQDATA (pattern 1), EQDATA (pattern 2), and EQDATA (pattern 3) in FIG. 9 arrive, it can be determined that the time width of the isolated bit is less than 1 UI. Whether or not the time width of the isolated bit is less than 1 UI is determined by the first phase comparison signal LAG (n−1) / LAG (n + 1) and the first phase comparison signal in the phase comparison window (n−1) and the phase comparison window (n + 1). The condition that the two phase comparison signals LEAD (n−1) / LEAD (n + 1) are both inactive, the first phase comparison signal LAG (n) and the second phase comparison in the phase comparison window (n) The determination can be made based on whether or not the condition that at least one of the signals LEAD (n) is activated is satisfied. When both of these conditions are satisfied, it is determined that the time width of the isolated bit is less than 1 UI, and the second adjustment signal EQADJ-UP is activated, while one or both of these conditions are satisfied. If not, it is determined that the time width of the isolated bit does not exceed 1 UI, and the second adjustment signal EQADJ-UP is not activated.

  The adaptive control filter unit 105 outputs the intensity adjustment signal EQADJ based on the first adjustment signal EQADJ-DN and the second adjustment signal EQADJ-UP output by the determination unit 104. The number of filter stages of the adaptive control filter unit 105 is three.

  FIG. 10 shows the state transition of the adaptive control filter unit 105. Each time the activated first adjustment signal EQADJ-DN is received, the state moves to the right, and every time the activated second adjustment signal EQADJ-UP is received, the state moves to the left. To do. When both the first adjustment signal EQADJ-DN and the second adjustment signal EQADJ-UP are in an inactive state, the state does not move. When the number of times of reception of the activated first adjustment signal EQADJ-DN exceeds the number of times of reception of the activated second adjustment signal EQADJ-UP by 3, that is, the number of filter stages (specified number), the equalizer unit The intensity adjustment signal EQADJ is changed by one step so that the equalization intensity of 11 is lowered. On the other hand, when the number of receptions of the activated second adjustment signal EQADJ-UP exceeds the number of receptions of the activated first adjustment signal EQADJ-DN by three times, that is, by the number of filter stages, The intensity adjustment signal EQADJ is changed by one step so as to increase the equalization intensity. After changing the intensity adjustment signal EQADJ, the state returns to the initial state. By mounting such an adaptive control filter unit 105, the operation at the time of locking can be further stabilized. The number of filter stages of the adaptive control filter unit 105 is not limited to three.

  Further, immediately after the connection between the adaptive reception system 10 and the adaptive transmission system 20, that is, immediately after the reception of the reception signal RXDATA by the adaptive reception system 10, the equalization intensity set by the intensity adjustment signal EQADJ can be set. It is an intermediate value between the highest value and the lowest value in the range of equalization strength.

  In addition, the pre-emphasis control unit 16 performs the adaptive type when the equalization intensity indicated by the intensity adjustment signal EQADJ output from the adaptive control filter unit 105 of the adaptive control unit 13 is equal to or greater than a preset upper limit threshold value. The control system CTRDT that requests the transmission system 20 to increase the pre-emphasis intensity by the pre-emphasis unit 23 is output via the control bus 40, and the equalization intensity indicated by the intensity adjustment signal EQADJ is When the value is equal to or lower than a preset lower limit threshold value, a second control is performed in which a control signal CTRDT requesting to reduce the pre-emphasis strength is output to the adaptive transmission system 20 via the control bus 40. If the equalization intensity indicated by the intensity adjustment signal EQADJ is not equal to or greater than the upper limit threshold value and the equalization intensity indicated by the intensity adjustment signal EQADJ is not equal to or less than the lower limit threshold value, the control signal CTRDT changes the intensity of the pre-emphasis. Will not be required.

  Specifically, the pre-emphasis control unit 16 includes a request signal generation unit 14 and an RX control unit 15.

  The request signal generation unit 14 compares the intensity adjustment signal EQADJ output from the adaptive control filter unit 105 with preset upper and lower thresholds, and the intensity adjustment signal EQADJ is greater than or equal to the preset upper threshold. Is determined, the request for increasing the pre-emphasis strength of the adaptive transmission system 20 is output as the request signal REQ. On the other hand, if it is determined by the comparison that the intensity adjustment signal EQADJ is less than or equal to a preset lower limit threshold, a request for reducing the pre-emphasis intensity of the adaptive transmission system 20 is output as the request signal REQ.

  The RX control unit 15 is an interface for communicating the control signal CTRDT via the control bus 40 with the TX control unit 22 of the adaptive transmission system 20. Specifically, the RX control unit 15 converts the request signal REQ output from the request signal generation unit 14 into the communication protocol of the control bus 40, and outputs the converted signal to the control bus 40 as the control signal CTRDT. . In the adaptive transmission / reception system 1, the differential transmission path 30 and the control bus 40 are realized by a common HDMI cable. The differential transmission path 30 and the control bus 40 are not limited to the HDMI cable, and may be realized by other cables or may be realized by cables independent of each other. The control signal CTRDT is transmitted from the adaptive reception system 10 to the adaptive transmission system 20, but the control bus 40 that transmits the control signal CTRDT may be a bidirectional bus.

  When the pre-emphasis control unit 16 is mounted, the pre-emphasis unit of the adaptive transmission system 20 can be used when the reception operation cannot be sufficiently stabilized only by the intensity adjustment of the equalizer unit 11 of the adaptive reception system 10. 23 can be adjusted, and as a result, the receiving operation of the adaptive receiving system 10 can be stabilized.

  The intensity adjustment signal EQADJ is represented by a Gray code as shown on the right side of FIG. As shown on the left side of FIG. 11, when the intensity adjustment signal EQADJ is a binary code, the number of bits that change during carry is large. For example, when the equalization intensity is switched from intensity 3 to intensity 4, it changes from 011 to 100, so that the total changes by 3 bits. If the equalizer unit 11 and the adaptive control unit 13 are physically separated from each other, the wiring distance and parasitic capacitance of the wiring for transmitting the signal of each digit are different from each other. It is set to a strength different from the strength. In this case, a glitch occurs in the equalization signal EQDATA, and an error occurs in the restoration signal RDOUT. However, in the first embodiment, since the intensity adjustment signal EQADJ is represented by the Gray code, the value of the intensity adjustment signal EQADJ changes only one bit at a time when the intensity is switched by one step. Therefore, even if the delay of each bit of the intensity adjustment signal EQADJ varies, the equalization intensity is set to the intensity before or after the change, and the glitch is hardly generated. Although it is impossible to obtain the effect of preventing glitches, the intensity adjustment signal EQADJ may be expressed by a method other than the gray code such as a binary code.

  The control bus 40 is a CEC (Consumer Electronics Control) bus. The CEC bus is a bus used for HDMI (High Definition Multimedia Interface). When the control signal CTRDT is transmitted from the adaptive reception system 10 to the adaptive transmission system 20, the adaptive reception system 10 becomes an initiator, and the adaptive transmission system 20 becomes a follower. In the present embodiment, a signal indicating a CEC message <Adjust PreEmphasis Increment> is used as the control signal CTRDT for increasing the pre-emphasis strength of the adaptive transmission system 20, and the pre-emphasis strength of the adaptive transmission system 20 is reduced. As the control signal CTRDT, a signal indicating a CEC message <Adjust PreEmphasis Decrement> is used. Note that the message for adjusting the pre-emphasis strength is not defined in the CEC in the HDMI standard Ver1.4a.

  A signal flow during transfer of the control signal CTRDT in the adaptive transmission / reception system 1 according to the first embodiment will be described with reference to FIG.

  First, when the request signal generation unit 14 of the adaptive reception system 10 outputs a request signal REQ that increases the strength of pre-emphasis, the RX control unit 15 converts the request signal REQ into a CEC protocol, and <Adjust PreEmphasis Increment> Send a message. Then, the TX control unit 22 of the adaptive transmission system 20 receives the <Adjust PreEmphasis Increment> message, and outputs an adjustment signal EMPADJ for increasing the pre-emphasis strength by one step to the pre-emphasis unit 23.

  On the other hand, when the request signal generation unit 14 of the adaptive reception system 10 outputs the request signal REQ for reducing the pre-emphasis strength, the RX control unit 15 converts the request signal REQ into a CEC protocol, and <Adjust PreEmphasis Decrement> Send a message. Then, the TX control unit 22 of the adaptive transmission system 20 receives the <Adjust PreEmphasis Decrement> message, and outputs an adjustment signal EMPADJ for reducing the pre-emphasis strength by one step to the pre-emphasis unit 23.

  If the adaptive transmission system 20 as a CEC follower does not support pre-emphasis intensity adjustment, the signal flow during the transfer of the control signal CTRDT is as shown in FIG.

  In such a case, when the request signal generation unit 14 of the adaptive reception system 10 outputs a request signal REQ that increases the strength of pre-emphasis, the RX control unit 15 converts the request signal REQ into a CEC protocol, and <Adjust PreEmphasis Increment> Send a message. Then, the TX control unit 22 of the adaptive transmission system 20 receives the message <Adjust PreEmphasis Increment>, recognizes that this message is a non-compliant message, and indicates that the received message is non-compliant <Feature. A message of “Abort>” is returned to the adaptive reception system 10.

  On the other hand, when the request signal generation unit 14 of the adaptive reception system 10 outputs a request signal REQ for reducing the pre-emphasis strength, the RX control unit 15 converts the request signal REQ into a CEC protocol, and <Adjust PreEmphasis Decrement> Send a message. Then, the TX control unit 22 of the adaptive transmission system 20 receives the message <Adjust PreEmphasis Decrement>, recognizes that this message is a non-compliant message, and indicates that the received message is non-compliant <Feature. A message of “Abort>” is returned to the adaptive reception system 10.

  The adaptive reception system 10 can recognize that the adaptive transmission system 20 does not support adaptive pre-emphasis intensity adjustment by receiving the <Feature Abort> message. Even when the adaptive transmission system 20 does not support adaptive pre-emphasis strength adjustment, the equalization strength of the equalizer can be adaptively adjusted in the adaptive reception system 10.

  In the present embodiment, the case where the control bus 40 is a CEC bus is illustrated, but the control bus 40 is not limited to the CEC bus.

<< Variation 1 of Embodiment 1 >>
In the adaptive transmission / reception system 1 according to the first modification of the first embodiment of the present invention, the request signal generation unit 14 is defined in advance with the intensity adjustment signal EQADJ output from the adaptive control filter unit 105 of the adaptive control unit 13. In addition to the magnitude relationship between the upper threshold and the lower threshold, the request signal REQ is output according to the activation state of the first adjustment signal EQADJ-DN and the second adjustment signal EQADJ-UP output by the determination unit 104. To do.

  Specifically, the request signal generation unit 14 of the first modification compares the intensity adjustment signal EQADJ output from the adaptive control filter unit 105 with preset upper and lower thresholds, and the intensity adjustment signal EQADJ. Is determined to be greater than or equal to a predetermined upper limit threshold value and the second adjustment signal EQADJ-UP is activated, a request for increasing the pre-emphasis strength of the adaptive transmission system 20 is used as the request signal REQ. Output. On the other hand, when it is determined by the comparison that the intensity adjustment signal EQADJ is equal to or lower than a predetermined lower threshold value and the first adjustment signal EQADJ-DN is activated, the pre-emphasis of the adaptive transmission system 20 is determined. A request to lower the intensity is output as a request signal REQ.

  According to the first modification, the request signal REQ is not output only when the intensity adjustment signal EQADJ is determined to be greater than or equal to the predetermined upper limit threshold value or when the intensity adjustment signal EQADJ is determined to be equal to or less than the predetermined lower limit threshold value. Therefore, the settable range of the intensity adjustment signal EQADJ can be widely used. Further, the output sensitivity of the request signal REQ can be finely controlled as compared with the first embodiment.

<< Modification 2 of Embodiment 1 >>
The adaptive transmission / reception system 1 according to the second modification of the first embodiment of the present invention includes an adaptive control unit 213 illustrated in FIG. 13 instead of the adaptive control unit 13 of the first embodiment.

  The adaptive control unit 213 includes a pattern detection unit 203, a determination unit 104, and an adaptive control filter unit 205.

  The pattern detection unit 203 detects the detection data patterns (1) to (8) in FIG. 14 and outputs a detection flag signal PTFLG having a value corresponding to the detected data pattern. Specifically, the pattern detection unit 203 outputs 1 to 8 as the detection flag signal PTFLG when the data patterns (1) to (8) are detected. If none of the data patterns (1) to (8) is detected, PTFLG = 0 is output. The adaptive control filter unit 205 includes eight filters 205a to 205h, a selection circuit 205i, and an OR circuit 205j, and the number of filter stages of the filters 205a to 205h is different from each other.

  The selection circuit 205i determines which filter 205a to 205h is used depending on the value of the detection flag signal PTFLG, that is, which of the data patterns (1) to (8) is detected by the pattern detection unit 203. decide. Then, the detection flag signal PTFLG and the first and second adjustment signals EQADJ-DN / EQADJ-UP are input to the filters 205a to 205h to be used. For example, when PTFLG = 1, a filter 205a having 128 filter stages is used, and when PTFLG = 8, a filter 205h having one filter stage is used. The outputs of the filters 205a to 205h are input to the OR circuit 205j, and the output of the OR circuit 205j becomes the intensity adjustment signal EQADJ. The type and number of detection data patterns, the value of the detection flag signal, and the number of filter stages are not limited to the above example.

  As shown in FIG. 7, the magnitude of distortion due to ISI strongly depends on the data pattern before the isolated bit. The distortion due to ISI increases as the value of k described above increases, and the distortion due to ISI decreases as the value of k decreases. In order to minimize the influence of ISI, it is necessary to perform waveform equalization so that the time width of an isolated bit is close to 1T without depending on the value of k. However, as the value of k increases as shown in FIG. The appearance probability of the data pattern decreases. When 0/1 appears at random, the appearance probability of each data is ½. Therefore, every time the value of k increases by 1, the appearance probability of the pattern is multiplied by ½.

  When the number of filter stages of the adaptive control filter unit 205 is fixed to one type, the first and second adjustment signals EQSET-DN / EQSET-UP are frequently activated for patterns having a high appearance probability. Therefore, the influence of ISI is sufficiently eliminated. However, on the contrary, since the appearance frequency of a pattern with a low appearance probability is low, the influence of ISI remains.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted. Further, as the request signal generation unit 14, the request signal generation unit 14 of the first modification may be used.

  According to the second modification, as shown in FIG. 14, filters having different numbers of stages are used according to the appearance probability of the detection data string. Specifically, every time the appearance probability of the detection data string increases twice, the number of stages of the filter also increases twice. Thus, the frequency at which the first and second adjustment signals EQSET-DN / EQSET-UP are activated is constant regardless of the data pattern, and the equalization intensity can be adjusted optimally.

<< Modification 3 of Embodiment 1 >>
In the adaptive transmission / reception system 1 according to the third modification of the first embodiment of the present invention, immediately after the connection between the adaptive reception system 10 and the adaptive transmission system 20, that is, immediately after the reception of the reception signal RXDATA by the adaptive reception system 10 is started. The equalization intensity of the equalizer unit 11 set by the intensity adjustment signal EQADJ is the lowest value within the settable equalization intensity range.

  According to the third modification, immediately after the reception of the reception signal RXDATA by the adaptive reception system 10 is started, the control signal CTRDT requesting to increase the strength of the pre-emphasis by the pre-emphasis unit 23 of the adaptive transmission system 20 is output. Pre-emphasis strength is increased. Then, according to this, the equalization intensity | strength of the equalizer part 11 of the adaptive type reception system 10 is made low. Therefore, while the transmission / reception of the reception signal RXDATA is continued, the adjustable range of the equalization intensity of the equalizer unit 11 of the adaptive reception system 10 can be secured widely, and the jitter tolerance can be increased.

<< Modification 4 of Embodiment 1 >>
In the adaptive transmission / reception system 1 according to the fourth modification of the first embodiment of the present invention, immediately after the connection between the adaptive reception system 10 and the adaptive transmission system 20, that is, immediately after the reception of the reception signal RXDATA by the adaptive reception system 10 is started. The pre-emphasis intensity of the pre-emphasis unit 23 set by the intensity adjustment signal EMPADJ is the highest value in the range of intensity that can be set by the pre-emphasis unit 23 of the adaptive transmission system 20.

  According to the fourth modification, immediately after the reception of the reception signal RXDATA by the adaptive reception system 10 is started, the pre-emphasis strength of the adaptive transmission system 20 is increased, so that the strength adjustment signal EQADJ is equalized to the equalization strength of the equalizer unit 11. It works to lower. Therefore, while the transmission / reception of the reception signal RXDATA is continued, the adjustable range of the equalization intensity of the equalizer unit 11 of the adaptive reception system 10 can be secured widely, and the jitter tolerance can be increased.

<< Other Modifications of Embodiment 1 >>
In the first embodiment, the 3-bit restoration signal RDOUT and the phase comparison signal LAG / LEAD are used for the adaptive control (equalization intensity adjustment) of the equalizer unit 11, but the restoration signal RDOUT for 4 bits or more is used. Alternatively, the phase comparison signal LAG / LEAD may be used.

  When the equalizer unit 11 is configured by connecting a plurality of stages of the circuit shown in FIG. 4A, the zero points of the equalizers in each stage are often arranged at different frequencies. By monitoring the output state of three or more consecutive bits, the equalization intensity at each stage can be adjusted independently. For example, when a bit string including an isolated bit is used to determine whether the bit time width of the equalization signal EQDATA is longer or shorter than 1 UI (010, 101), since the bit string includes the highest frequency component, the zero point is Adjust the equalization strength of the stage located at the highest frequency. On the other hand, in the case of using a bit string including two consecutive bits of the same value between two bit inversions (0110, 1001) for determining whether the bit time width of the equalization signal EQDATA is longer or shorter than 1 UI (0110, 1001) Since this bit string includes a lower frequency component than the bit string including the isolated bit, the equalization intensity of the stage where the zero point is arranged at the second highest frequency is adjusted. As described above, as the number of consecutive identical values between two inversions increases, the frequency component included in the signal becomes lower, so that the equalization intensity of each stage of the equalizer unit 11 can be adjusted independently. Thereby, the equalization characteristic of the equalizer part 11 can be adjusted to a more optimal state.

<< Embodiment 2 >>
FIG. 15 shows a multiple channel transmission / reception system 2 according to Embodiment 2 of the present invention. The multi-channel transmission / reception system 2 includes three sets of adaptive transmission / reception systems 1a to 1c. The adaptive transmission / reception systems 1a to 1c have the same configuration as the adaptive transmission / reception system 1 according to the first embodiment.

  The three sets of differential transmission paths 30 and the control bus 40 included in the multi-channel transmission / reception system 2 are realized by a common HDMI cable. However, the three sets of differential transmission paths 30 and the control bus 40 are not limited to HDMI cables, and may be realized by other cables or may be realized by cables independent of each other.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  According to the second embodiment, the strength of the equalizer unit 11 and the pre-emphasis unit 23 corresponding to each of the three sets of differential transmission paths 30 can be adjusted independently to optimize the strength.

  In the second embodiment, the multi-channel transmission / reception system 2 includes the three adaptive transmission / reception systems 1a to 1c. However, the number of the adaptive transmission / reception systems 1 is not limited to three, and may be two. There may be four or more sets. Even in this case, it is possible to optimize the strength of the equalizer unit 11 and the pre-emphasis unit 23 corresponding to each differential transmission path 30.

  The adaptive reception system and adaptive transmission / reception system according to the present invention are useful for an ultrahigh-speed transmission system exceeding Gb / s, for example.

1 Adaptive transmission / reception system
2 Multiple channel transmission / reception system 10 Adaptive reception system
11 Equalizer section
16 Pre-emphasis control unit 20 Adaptive transmission system
101 Phase comparator
102 Clock adjustment unit
103 Pattern detector
104 judgment part
105 Filter section for adaptive control
203 pattern detector
205 Filter part for adaptive control
213 Adaptive control unit
231 Amplifier 232 Amplifier 233 Adder

Claims (21)

A transmission signal output by the adaptive transmission system is received as a reception signal through a differential transmission path, and the transmission signal is obtained by pre-emphasis on the logical signal by the adaptive transmission system. An adaptive receiver system,
An equalizer for equalizing the received signal based on an intensity adjustment signal indicating equalized intensity and outputting the equalized signal;
Based on the sampling clock and the first clock that is advanced by the first predetermined phase from the sampling clock, the first interval between the sampling timing and the timing that is the first predetermined phase before the sampling timing And outputting a first phase comparison signal indicating whether or not an edge of the equalization signal exists, and based on the sampling clock and a second clock delayed by a second predetermined phase from the sampling clock And outputting a second phase comparison signal indicating whether or not an edge of the equalized signal is present in the second interval between the sampling timing and the timing after the second predetermined phase from the sampling timing. The first section and the second section are in a state in which the phases of the equalized signal and the sampling clock match. A phase comparator which is set so as not to include an edge of the equalized signal,
Based on the first and second phase comparison signals, a clock adjustment unit that adjusts and outputs the phase of the sampling clock to match the phase of the equalization signal and the sampling clock;
A pattern detection unit that detects a detection data pattern of three or more consecutive bits including at least two bit inversions from a restored signal obtained by sampling the equalization signal with the sampling clock;
The output pattern of the first and second phase comparison signals corresponding to each bit of the detection data pattern detected by the pattern detection unit is compared with a predetermined comparison target pattern, based on whether or not they match, A determination unit for determining whether the bit time width of the equalized signal is longer or shorter than 1 UI;
An adaptive control filter unit that adjusts the intensity adjustment signal based on a determination result by the determination unit;
A first control for outputting to the adaptive transmission system a control signal requesting to increase the pre-emphasis strength when the equalization strength indicated by the strength adjustment signal is equal to or higher than a preset upper threshold; A second control for outputting to the adaptive transmission system a control signal requesting to lower the pre-emphasis intensity when the equalization intensity indicated by the intensity adjustment signal is equal to or lower than a preset lower threshold; And a pre-emphasis control unit that executes at least one of the adaptive reception system. The adaptive receiving system according to claim 1,
The first control is performed when the determination unit does not determine that the bit time width of the equalization signal is shorter than 1 UI even if the equalization intensity indicated by the intensity adjustment signal is equal to or greater than the upper limit threshold. Does not output to the adaptive transmission system a control signal requesting to increase the strength of the pre-emphasis. The adaptive receiving system according to claim 1,
The second control is performed when the determination unit does not determine that the bit time width of the equalization signal is longer than 1 UI even if the equalization intensity indicated by the intensity adjustment signal is equal to or less than the lower threshold. Does not output to the adaptive transmission system a control signal requesting that the pre-emphasis intensity be reduced. The adaptive receiving system according to any one of claims 1 to 3,
The length of the said 1st area and the 2nd area is 1/3 UI or less, The adaptive reception system characterized by the above-mentioned. The adaptive receiving system according to any one of claims 1 to 4,
The adaptive data receiving system according to claim 1, wherein the detected data pattern detected by the pattern detecting unit includes three consecutive bits whose central bit value is different from the preceding and following bit values. The adaptive receiving system according to claim 5,
The detection data pattern detected by the pattern detection unit includes two or more consecutive bits having the same value before the central bit. The adaptive receiving system according to claim 5,
The comparison target pattern indicates that the second phase comparison signal corresponding to the bit immediately before the central bit indicates that an edge exists, and the first and second phase comparisons corresponding to the central bit The signals indicate that none of the edges are present,
The determination unit determines that a bit time width of the equalized signal is longer than 1 UI when the output pattern matches the comparison target pattern. The adaptive receiving system according to claim 5,
The comparison target pattern indicates that the first phase comparison signal corresponding to the bit immediately after the central bit indicates that an edge exists, and the first and second phase comparisons corresponding to the central bit The signals indicate that none of the edges are present,
The determination unit determines that a bit time width of the equalized signal is longer than 1 UI when the output pattern matches the comparison target pattern. The adaptive receiving system according to claim 5,
In the comparison target pattern, one of the first and second phase comparison signals corresponding to the central bit indicates that an edge exists, and the first bit corresponding to the bit immediately before and after the central bit corresponds to the first bit. And the second phase comparison signal indicates that no edge exists,
The determination unit determines that a bit time width of the equalized signal is shorter than 1 UI when the output pattern matches the comparison target pattern. The adaptive receiving system according to claim 5,
The comparison target pattern indicates that both the first and second phase comparison signals corresponding to the central bit indicate that an edge exists, and the first and second corresponding to the bits immediately before and after the central bit. The phase comparison signals of, indicate that there are no edges,
The determination unit determines that a bit time width of the equalized signal is shorter than 1 UI when the output pattern matches the comparison target pattern. The adaptive receiving system according to any one of claims 5 to 10,
In the adaptive control filter unit, when the determination unit determines that the bit time width of the equalized signal is longer than 1 UI, the determination unit determines that the bit time width of the equalized signal is shorter than 1 UI. When the determined number exceeds the predetermined number of times, the intensity adjustment signal is changed so as to lower the equalization intensity, while the bit time width of the equalization signal is shorter than 1 UI by the determination unit. When the number of times determined by the determination unit exceeds the number of times determined by the determination unit that the bit time width of the equalized signal is longer than 1 UI by the predetermined number of times, the equalization strength is increased. An adaptive receiving system characterized by changing an intensity adjustment signal. The adaptive receiving system according to claim 11,
The pattern detection unit detects a plurality of types of detection data patterns,
The adaptive control filter unit includes a selection circuit that determines the predetermined specified number of times according to which of the plurality of types of detection data patterns is detected by the pattern detection unit. Adaptive receiving system. The adaptive receiving system according to any one of claims 1 to 12,
The adaptive receiving system according to claim 1, wherein the intensity adjustment signal represents intensity by a Gray code. The adaptive receiving system according to any one of claims 1 to 13,
Immediately after the reception of the received signal is started, the equalization intensity set by the intensity adjustment signal is an intermediate value between the highest value and the lowest value in the settable equalization intensity range. system. The adaptive receiving system according to any one of claims 1 to 13,
Immediately after the reception of the reception signal is started, the equalization intensity set by the intensity adjustment signal is the lowest value within a settable equalization intensity range. An adaptive receiving system according to any one of claims 1 to 15,
The adaptive transmission system;
The differential transmission line;
An adaptive transmission / reception system comprising: a control bus for transmitting a control signal output by a pre-emphasis control unit of the adaptive reception system to the adaptive transmission system. The adaptive transmission / reception system according to claim 16,
Pre-emphasis by the adaptive transmission system is
At least one amplifier for amplifying the logic signal at an amplification factor according to the control signal;
An adaptive transmission / reception system comprising: an adder that adds outputs of the at least one amplifier and outputs a result of the addition as the reception signal. The adaptive transmission / reception system according to claim 16 or 17,
Immediately after the reception of the received signal by the adaptive reception system, the pre-emphasis intensity is set to an intermediate value between the maximum value and the minimum value in the pre-emphasis intensity range that can be set by the adaptive transmission system. An adaptive transmission / reception system characterized by the above. The adaptive reception system according to claim 16 or 17,
Immediately after the reception of the received signal by the adaptive reception system, the pre-emphasis strength is set to the highest value in the pre-emphasis strength range that can be set by the adaptive transmission system. Transmission / reception system. The adaptive transmission / reception system according to any one of claims 16 to 19,
The adaptive transmission / reception system, wherein the control bus is a CEC (Consumer Electronics Control) bus.   A multi-channel transmission / reception system comprising a plurality of adaptive transmission / reception systems according to any one of claims 16 to 20.

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