CN-121690264-B - Signal cancellation circuit, signal cancellation method, and interface circuit

CN121690264BCN 121690264 BCN121690264 BCN 121690264BCN-121690264-B

Abstract

The application discloses a signal cancellation circuit, a signal cancellation method and an interface circuit. The signal cancellation circuit is applied to a full duplex transmit receive circuit comprising a transmitter for providing a first channel differential signal to a communication link in dependence on an input signal and a receiver for receiving a second channel differential signal over the communication link. The signal cancellation circuit comprises a signal suppression unit connected with the differential input end of the receiver and used for providing reverse suppression differential signals for the differential input end of the receiver according to the input signals, and a residual calibration unit used for obtaining residual signals between the first channel differential signals and the reverse suppression differential signals in a calibration stage and adjusting the amplitude of the reverse suppression differential signals according to offset characteristic values of the residual signals in a feedback mode. By feedback adjustment of the reverse suppressed differential signal, communication quality can be improved.

Inventors

GUO XIAOMEI
YANG JIWU
ZHOU YI

Assignees

锐泰微(北京)电子科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260206

Claims (11)

1. A signal cancellation circuit for a full duplex transmit receive circuit, the full duplex transmit receive circuit comprising a transmitter for providing a first channel differential signal to a communication link in dependence upon an input signal and a receiver for receiving a second channel differential signal over the communication link, wherein the signal cancellation circuit comprises: a signal suppressing unit connected to the differential input terminal of the receiver for providing a reverse suppressed differential signal to the differential input terminal of the receiver according to the input signal, and A residual calibration unit, configured to obtain a residual signal between the first channel differential signal and the reverse suppressed differential signal in a calibration stage, and adjust an amplitude of the reverse suppressed differential signal in a feedback manner according to an offset characteristic value of the residual signal, Wherein the residual calibration unit comprises: The signal overturning module is used for overturning the negative polarity waveforms in the residual signals into positive polarity waveforms so as to obtain signals to be detected of full positive polarity waveforms; a comparison module for comparing the deviation of the peak value of each positive waveform compared with the reference value in the signal to be detected, and taking the maximum value/minimum value/median value/average value as the characteristic value of the deviation And the adjusting module is used for providing an adjusting signal according to the offset characteristic value, and the adjusting signal is used for adjusting the current source in the signal suppression unit.
2. The signal cancellation circuit of claim 1, wherein, In the calibration phase, the second channel differential signal is a common mode signal, the receiver's received signal is the residual signal, The residual calibration unit is connected between the signal suppression unit and a differential input of the receiver to receive the residual signal.
3. The signal cancellation circuit of claim 2, wherein the signal cancellation circuit further comprises: And the first amplifying module is used for providing the amplified residual signal for the signal overturning module.
4. The signal cancellation circuit of claim 2, wherein the signal cancellation circuit further comprises: and the filtering module is used for filtering the signal to be detected.
5. The signal cancellation circuit of claim 2 wherein, The signal inversion module operates in the analog domain, the comparison module and the adjustment module operate in the digital domain, The signal cancellation circuit further includes: and the analog-to-digital conversion module is used for converting the signal to be detected of the analog signal type into the signal to be detected of the digital signal type.
6. The signal cancellation circuit of claim 5, wherein the signal cancellation circuit further comprises: And the second amplifying module is used for amplifying the signal to be detected before analog-to-digital conversion.
7. The signal cancellation circuit of claim 2, wherein the signal suppression unit comprises: the current source; A differential pair of transistors including a first transistor and a second transistor, a first end of the first transistor being connected to one input end of the receiver, a control end being connected to one of the input signals; the first end of the second transistor is connected with the other input end of the receiver, the control end of the second transistor is connected with the other input end of the input signal, and the second end of the first transistor is connected with the second end of the second transistor and is connected with the current source; a first resistor, a first end of the first transistor being connected to an output end of the transmitter via the first resistor, and And the first end of the second transistor is connected with the other output end of the transmitter through the second resistor.
8. An interface circuit for a full duplex transmit receive circuit, wherein the full duplex transmit receive circuit comprises the interface circuit, the interface circuit comprising: A transmitter for providing a first channel differential signal to the communication link in accordance with the input signal; A receiver for receiving a second channel differential signal over the communication link, and The signal cancellation circuit of any one of claims 1-7, coupled between the communication link and the receiver, for providing the reverse suppressed differential signal to a differential input of the receiver, the reverse suppressed differential signal for canceling the first channel differential signal mixed in the second channel differential signal, Wherein the first channel is a forward channel and the second channel is a reverse channel.
9. An interface circuit for a full duplex transmit receive circuit, wherein the full duplex transmit receive circuit comprises the interface circuit, the interface circuit comprising: A transmitter for providing a first channel differential signal to the communication link in accordance with the input signal; A receiver for receiving a second channel differential signal over the communication link, and The signal cancellation circuit of any one of claims 1-7, coupled between the communication link and the receiver, for providing the reverse suppressed differential signal to a differential input of the receiver, the reverse suppressed differential signal for canceling the first channel differential signal mixed in the second channel differential signal, Wherein the first channel is a reverse channel and the second channel is a forward channel.
10. A signal cancellation method for a full duplex transmit receive circuit, the full duplex transmit receive circuit comprising a transmitter for providing a first channel differential signal to a communication link in accordance with an input signal and a receiver for receiving a second channel differential signal over the communication link, wherein the signal cancellation method comprises: providing a reverse suppressed differential signal to a differential input of the receiver based on the input signal; Obtaining a residual signal between the first channel differential signal and the reverse suppressed differential signal during a calibration phase, and The amplitude of the reverse inhibition differential signal is adjusted according to the offset characteristic value feedback of the residual signal, Wherein the step of obtaining the offset characteristic value includes: Turning negative polarity waveforms in the residual signals into positive polarity waveforms to obtain signals to be detected of full positive polarity waveforms; And comparing the offset of the peak value of each positive polarity waveform in the signal to be detected compared with a reference value, and taking the maximum value/minimum value/median value/mean value of the peak value of each positive polarity waveform as the characteristic value of the offset.
11. The signal cancellation method of claim 10, wherein the step of obtaining the residual signal comprises: Providing a common mode signal as the second channel differential signal during the calibration phase, and And taking a receiving signal of the receiver as the residual signal.

Description

Signal cancellation circuit, signal cancellation method, and interface circuit Technical Field The present application relates to the field of electronic devices, and in particular, to a signal cancellation circuit, a signal cancellation method, and an interface circuit. Background A full duplex transmitting and receiving circuit is a circuit capable of transmitting and receiving signals simultaneously. In particular, full duplex transmit receive circuitry typically includes a first interface circuit and a second interface circuit communicatively connected via a communication link. Fig. 1 shows a schematic block diagram of any interface circuit 10 of the prior art. As shown IN fig. 1, the first and/or second interface circuit has a transmitter 11 for providing a first channel differential signal to the communication link 13 IN dependence of the input signals TX-IN and TX-IP, and a receiver 12 for receiving a second channel differential signal over the communication link 13. Wherein, the signal transmission directions of the first channel and the second channel are opposite, thereby realizing bidirectional communication. Since both the transmitter 11 and the receiver 12 are connected to the communication link 13, the first channel differential signal transmitted by the transmitter 11 will cause self-interference to the second channel differential signal received by the receiver 12. In the prior art, the interface circuit 10 also has a signal cancellation circuit 14 to cancel such self-interference. As shown in fig. 1, the signal cancellation circuit 14 has therein a pair of resistors R1 and R2, a pair of differential transistors M1 and M2, and a current source I1. The signal cancellation circuit 14 is operative to generate inverse-suppressed differential signals based on the input signals TX-IN and TX-IP. The signal cancellation circuit 14 is connected to the differential input terminals of the receiver 12, and cancels the first channel differential signal in the received signal of the receiver 12 by suppressing the differential signal in the opposite direction. However, due to factors such as device mismatch, temperature drift and process deviation, the reverse suppression differential signal is difficult to completely match with the actual interference of the first channel differential signal to the second channel differential signal, and the communication quality is very affected. Disclosure of Invention In view of the foregoing, an object of the present application is to provide a signal cancellation circuit, a signal cancellation method, and an interface circuit, which can improve communication quality. According to an aspect of the present invention there is provided a signal cancellation circuit for a full duplex transmit receive circuit comprising a transmitter for providing a first channel differential signal to a communication link in dependence on an input signal and a receiver for receiving a second channel differential signal over the communication link, wherein the signal cancellation circuit comprises a signal suppression unit connected to differential inputs of the receiver for providing a reverse suppressed differential signal to the differential inputs of the receiver in dependence on the input signal, and a residual calibration unit for obtaining a residual signal between the first channel differential signal and the reverse suppressed differential signal during a calibration phase and for feedback adjusting the amplitude of the reverse suppressed differential signal in dependence on an offset characteristic value of the residual signal. Optionally, in the calibration phase, the second channel differential signal is a common mode signal, the receiving signal of the receiver is the residual signal, and the residual calibration unit is connected between the signal suppression unit and the differential input terminal of the receiver to receive the residual signal. Optionally, the residual calibration unit comprises a signal overturning module, a comparison module and an adjusting module, wherein the signal overturning module is used for overturning negative polarity waveforms in a plurality of residual signals into positive polarity waveforms to obtain signals to be detected of full positive polarity waveforms, the comparison module is used for comparing the offset of the peak value of each positive polarity waveform in the signals to be detected compared with a reference value, the maximum value/minimum value/median value/average value of the peak value of each positive polarity waveform is used as the offset characteristic value, and the adjusting module is used for providing an adjusting signal according to the offset characteristic value, and the adjusting signal is used for adjusting a current source in the signal suppression unit. Optionally, the signal elimination circuit further comprises a first amplifying module, which is used for providing the amplified residual signal to the signa