# US 12,602,068 B2 · Signal processing device and operating method thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,602,068 B2 - Document ID: US12602068B2 - Status: Granted - Kind: B2 - Application number: 18/966,164 - Filed: 2024-12-03 - Published: 2025-06-12 - Granted: 2026-04-14 - Earliest claimed: 2023-12-07 - Assignees: Realtek Semiconductor Corp. - Applicants: Realtek Semiconductor Corporation - Inventors: Zhen Cheng Zhang; Chih-Lung Chen - Web page: https://patentgrep.com/patent/US12602068B2 ## CPC - G05F 1/567: for temperature compensation - H04B 1/04: Circuits - H04B 2001/0416: {having gain or transmission power control} - H04B 2001/0491: {with frequency synthesizers, frequency converters or modulators} - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES - H04B: TRANSMISSION ## Abstract A signal processing device includes a circuit system, in which the circuit system includes an amplifier, a temperature compensating circuit and a computing circuit. The amplifier is configured to amplify an input signal according to a temperature compensating current, in order to generate an output signal. A direct current offset of the output signal is related to the temperature compensating current. The temperature compensating circuit includes a detecting resistor and a comparator. The detecting resistor is configured to generate a detecting voltage according to the temperature compensating current. The comparator is configured to compare the detecting voltage with a reference voltage to generate a comparison signal. The computing circuit is configured to adjust the temperature compensating current according to the comparison signal so as to make the detecting voltage approximate to the reference voltage. ## Claims ### Claim 1 A signal processing device, comprising a circuit system, wherein the circuit system comprises: an amplifier, configured to amplify an input signal according to a temperature compensating current for generating an output signal, wherein a direct current offset of the output signal is related to the temperature compensating current; and a temperature compensating circuit, comprising: a detecting resistor, configured to generate a detecting voltage according to the temperature compensating current; and a comparator, configured to compare the detecting voltage with a reference voltage to generate a comparison signal; and a computing circuit, configured to adjust the temperature compensating current according to the comparison signal so as to make the detecting voltage approximate to the reference voltage. ### Claim 2 (depends on 1) The signal processing device according to claim 1, wherein a first input terminal and a second input terminal of the amplifier are configured to receive the input signal, a first gain compensating current and a second gain compensating current, wherein the direct current offset of the output signal of the amplifier is related to the first gain compensating current and the second gain compensating current, and wherein the amplifier is configured to adjust a gain of the amplifier according to a gain control signal, and the computing circuit is configured to adjust the first gain compensating current and the second gain compensating current according to the gain control signal. ### Claim 3 (depends on 1) The signal processing device according to claim 1, wherein the reference voltage is a bandgap reference voltage. ### Claim 4 (depends on 1) The signal processing device according to claim 1, further comprising: a frequency mixer coupled with the amplifier, and the frequency mixer being configured to convert a first radio-frequency signal into a first baseband signal and configured to output the first baseband signal as the input signal to the amplifier; and a receiving terminal baseband circuit coupled with the amplifier, and the receiving terminal baseband circuit being configured to filter the output signal. ### Claim 5 (depends on 1) The signal processing device according to claim 1, further comprising: a digital-to-analog converter coupled with the amplifier, and the digital-to-analog converter being configured to output a second baseband signal and configured to output the second baseband signal as the input signal to the amplifier; and a transmitting terminal baseband circuit coupled with the amplifier, and the transmitting terminal baseband circuit being configured to filter the output signal. ### Claim 6 (depends on 1) The signal processing device according to claim 1, wherein the temperature compensating circuit further comprises: a first switching circuit coupled with the detecting resistor, and the first switching circuit being configured to transfer one of a first candidate current and a second candidate current as the temperature compensating current to the detecting resistor, so that the detecting resistor generates the detecting voltage, wherein the amplifier utilizes the one of the first candidate current and the second candidate current to adjust the direct current offset of the output signal of the amplifier, and wherein the first candidate current is different from the second candidate current. ### Claim 7 (depends on 6) The signal processing device according to claim 6, wherein the first candidate current and the second candidate current have different temperature coefficients. ### Claim 8 (depends on 6) The signal processing device according to claim 6, further comprising: a frequency mixer; a transmitting terminal baseband circuit; a receiving terminal baseband circuit; a digital-to-analog converter; a second switching circuit coupled with the amplifier and configured to transfer the input signal to the amplifier; and a third switching circuit coupled with the amplifier and configured to receive the output signal, wherein in response to that the first switching circuit transfers the first candidate current as the temperature compensating current to the detecting resistor, the second switching circuit outputs a first baseband signal generated by the frequency mixer as the input signal, and the third switching circuit transfers the output signal to the receiving terminal baseband circuit, and wherein in response to that the first switching circuit transfers the second candidate current as the temperature compensating current to the detecting resistor, the second switching circuit outputs a second baseband signal generated by the digital-to-analog converter as the input signal, and the third switching circuit transfers the output signal to the transmitting terminal baseband circuit. ### Claim 9 (depends on 1) The signal processing device according to claim 1, wherein the amplifier is a transimpedance amplifier. ### Claim 10 An operating method applicable to a signal processing device, wherein the signal processing device comprises a circuit system, and the circuit system comprises an amplifier, a temperature compensating circuit and a computing circuit, and the operating method comprises: utilizing the amplifier to amplify an input signal of the amplifier according to a temperature compensating current, wherein a direct current offset of an output signal of the amplifier is related to the temperature compensating current; utilizing a detecting resistor of the temperature compensating circuit to generate a detecting voltage according to the temperature compensating current; utilizing a comparator of the temperature compensating circuit to compare the detecting voltage with a reference voltage to generate a comparison signal; and utilizing the computing circuit to adjust the temperature compensating current according to the comparison signal so as to make the detecting voltage approximate to the reference voltage. ### Claim 11 (depends on 10) The operating method according to claim 10, wherein utilizing the amplifier to amplify the input signal of the amplifier according to the temperature compensating current to generate the output signal comprises: utilizing a first input terminal and a second input terminal of the amplifier to receive the input signal, a first gain compensating current and a second gain compensating current, wherein the direct current offset of the output signal is related to the first gain compensating current and the second gain compensating current; utilizing the amplifier to adjust a gain of the amplifier according to a gain control signal; and utilizing the computing circuit to adjust the first gain compensating current and the second gain compensating current according to the gain control signal. ### Claim 12 (depends on 10) The operating method according to claim 10, wherein the reference voltage is a bandgap reference voltage. ### Claim 13 (depends on 10) The operating method according to claim 10, wherein the signal processing device further comprises a frequency mixer and a receiving terminal baseband circuit, wherein the operating method further comprises: utilizing the frequency mixer to convert a first radio-frequency signal into a first baseband signal, wherein the first baseband signal is outputted to the amplifier as the input signal; and utilizing the receiving terminal baseband circuit to filter the output signal. ### Claim 14 (depends on 10) The operating method according to claim 10, wherein the signal processing device further comprises a digital-to-analog converter and a transmitting terminal baseband circuit, wherein the operating method further comprises: utilizing the digital-to-analog converter to generate a second baseband signal, wherein the second baseband signal is outputted to the amplifier as the input signal; and utilizing the transmitting terminal baseband circuit to filter the output signal. ### Claim 15 (depends on 10) The operating method according to claim 10, wherein the signal processing device further comprises a first switching circuit, and the operating method further comprises: in response to that the first switching circuit transfers one of a first candidate current and a second candidate current as the temperature compensating current to the detecting resistor, so that the detecting resistor generates the detecting voltage, utilizing, by the amplifier, the one of the first candidate current and the second candidate current to adjust the direct current offset of the output signal of the amplifier, and wherein the first candidate current is different from the second candidate current. ### Claim 16 (depends on 15) The operating method according to claim 15, wherein the first candidate current and the second candidate current have different temperature coefficients. ### Claim 17 (depends on 15) The operating method according to claim 15, wherein the signal processing device further comprises a frequency mixer, a receiving terminal baseband circuit, a transmitting terminal baseband circuit, a digital-to-analog converter, a second switching circuit and a third switching circuit, the second switching circuit and the third switching circuit are coupled with the amplifier, wherein the operating method further comprises: in response to that the first switching circuit transfers the first candidate current as the temperature compensating current to the detecting resistor: utilizing the second switching circuit to output a first baseband signal generated by the frequency mixer as the input signal; and utilizing the third switching circuit to transfer the output signal to the receiving terminal baseband circuit; and in response to that the first switching circuit transfers the second candidate current as the temperature compensating current to the detecting resistor: utilizing the second switching circuit to output a second baseband signal generated by the digital-to-analog converter as the input signal; and utilizing the third switching circuit to transfer the output signal to the transmitting terminal baseband circuit. ### Claim 18 (depends on 10) The operating method according to claim 10, wherein the amplifier is a transimpedance amplifier.