# US 12,184,241 B2 · Systems and methods for suppressing and mitigating harmonic distortion in a circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,184,241 B2 - Document ID: US12184241B2 - Status: Granted - Kind: B2 - Application number: 18/232,343 - Filed: 2023-08-09 - Published: 2023-12-14 - Granted: 2024-12-31 - Earliest claimed: 2018-03-15 - Assignees: Taiwan Semiconductor Manufacturing Company, Ltd. - Applicants: Taiwan Semiconductor Manufacturing Co., Ltd. - Inventors: Feng-Wei Kuo; Kai Xu; Robert Bogdan Staszewski - Web page: https://patentgrep.com/patent/US12184241B2 ## CPC - H03F 1/565: {using inductive elements} - H03F 3/245: {with semiconductor devices only} - H03F 3/20: Power amplifiers, e.g. Class B amplifiers, Class C amplifiers (H03F3/26 - H03F3/30 take precedence) - H03F 3/2176: {Class E amplifiers} - H03F 3/45: Differential amplifiers (differential sense amplifiers G11C7/062) - H03F 2200/451: the amplifier being a radio frequency amplifier - H03F: AMPLIFIERS ## Abstract Systems and methods for suppressing and mitigating harmonic distortion in a circuit are disclosed. In one example, a disclosed circuit includes a radio frequency (RF) oscillator and a power amplifier. The RF oscillator is configured to generate an RF signal. The power amplifier is configured to generate an amplified RF signal based on the RF signal. The power amplifier includes a transformer including a primary winding and a secondary winding, and a feedback capacitor electrically coupled to the primary winding and the secondary winding. ## Claims ### Claim 1 A circuit, comprising: a radio frequency (RF) oscillator configured to generate an RF signal; a power amplifier configured to generate an amplified RF signal based on the RF signal, wherein the power amplifier is configured to generate the amplified RF signal based on the clock signal, and wherein the power amplifier comprises: a transformer including a primary winding and a secondary winding, and a feedback capacitor electrically coupled to the primary winding and the secondary winding; and a frequency divider that is coupled between the RF oscillator and the power amplifier, wherein: the frequency divider is configured to generate a clock signal having an average frequency representing a frequency of the RF signal divided by two. ### Claim 2 (depends on 1) The circuit of claim 1, wherein: the RF oscillator comprises a compensating circuit configured to control a bias voltage to mitigate a magnetic coupling with respect to at least one harmonic injection from the power amplifier to the RF oscillator. ### Claim 3 (depends on 1) The circuit of claim 1, wherein the RF oscillator is a digitally controlled oscillator (DCO) that generates the RF signal according to an oscillator tuning word. ### Claim 4 (depends on 1) The circuit of claim 1, wherein the power amplifier is a single-ended differential digital power amplifier (DPA). ### Claim 5 (depends on 1) The circuit of claim 1, wherein the feedback capacitor enhances a feedback coupling from the secondary winding to the primary winding to suppress at least one harmonic distortion of the amplified RF signal. ### Claim 6 (depends on 5) The circuit of claim 5, wherein the at least one harmonic distortion comprises a second-order harmonic distortion (HD2) of the amplified RF signal. ### Claim 7 (depends on 5) The circuit of claim 5, wherein the power amplifier comprises a matching network having a loaded quality factor that is high enough such that a third-order harmonic distortion (HD3) of the amplified RF signal is suppressed below a given threshold by the feedback capacitor. ### Claim 8 (depends on 1) The circuit of claim 1, wherein the transformer of the power amplifier is placed within an inner diameter of a transformer of the RF oscillator according to a concentric layout topology. ### Claim 9 (depends on 1) The circuit of claim 1, the RF oscillator comprises a coil magnetically coupled between the primary winding and the secondary winding. ### Claim 10 A circuit, comprising: a radio frequency (RF) oscillator configured to generate an RF signal; and a power amplifier configured to generate an amplified RF signal based on the RF signal, wherein: the power amplifier comprises a first transformer including a first primary winding and a first secondary winding, and the RF oscillator is a digitally controlled oscillator (DCO) that generates the RF signal according to an oscillator tuning word. ### Claim 11 (depends on 10) The circuit of claim 10, wherein: the RF oscillator comprises a compensating circuit configured to control a bias voltage to mitigate a magnetic coupling with respect to at least one harmonic injection from the power amplifier to the RF oscillator. ### Claim 12 (depends on 10) The circuit of claim 10, wherein the at least one harmonic injection comprises a second-order harmonic injection to the RF oscillator. ### Claim 13 (depends on 12) The circuit of claim 12, further comprising a frequency divider that is coupled between the RF oscillator and the power amplifier and configured to generate a clock signal having an average frequency representing a frequency of the RF signal divided by two, wherein the power amplifier is configured to generate the amplified RF signal based on the clock signal. ### Claim 14 (depends on 9) The circuit of claim 9, wherein the RF oscillator further comprises a second transformer including a second primary winding and a second secondary winding. ### Claim 15 (depends on 14) The circuit of claim 14, wherein: the RF oscillator comprises a coil magnetically coupled between the first primary winding in the power amplifier and the first secondary winding in the power amplifier; and the compensating circuit comprises: a first pair of transistors whose gates are coupled to two ends of the coil respectively, and a second pair of transistors whose gates are coupled to two ends of the second secondary winding respectively, wherein each of the second pair of transistors is connected to a respective one of the first pair of transistors in series. ### Claim 16 (depends on 14) The circuit of claim 14, wherein: the first transformer of the power amplifier is placed within an inner diameter of the second transformer of the RF oscillator according to a concentric layout topology; and a minimum distance is reserved between an outmost turn of the first transformer and an innermost turn of the second transformer to keep a coupling factor at a certain harmonic between the power amplifier and the RF oscillator below a given threshold. ### Claim 17 A method for suppressing harmonic distortions of a power amplifier comprising a transformer and a feedback capacitor, comprising: generating a first signal having a harmonic distortion at a primary winding of the transformer; sending the first signal through the feedback capacitor to generate a second signal at a secondary winding of the transformer; sending the second signal as a feedback to the primary winding through a magnetic coupling; and compensating the first signal with the second signal. ### Claim 18 (depends on 17) The method of claim 17, further comprising: sensing the magnetic coupling between the primary winding and the secondary winding by a coil magnetically coupled between the primary winding and the secondary winding. ### Claim 19 (depends on 18) The method of claim 18, further comprising: sending, by the coil, an amplified and inverted signal to the primary winding and the secondary winding, wherein the coil is electrically coupled to an oscillator. ### Claim 20 (depends on 19) The method of claim 19, further comprising: controlling a bias voltage associated with the coil to mitigate a magnetic coupling with respect to at least one harmonic injection from the power amplifier to the oscillator, wherein the second signal comprises a given order harmonic that is an inversion of a given order harmonic of the first signal.