# US 10,122,326 B2 · Systems and methods providing loadline modulation of a power amplifier > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,122,326 B2 - Document ID: US10122326B2 - Status: Granted - Kind: B2 - Application number: 15/472,504 - Filed: 2017-03-29 - Published: 2018-05-10 - Granted: 2018-11-06 - Earliest claimed: 2016-11-04 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Jose Cabanillas - Web page: https://patentgrep.com/patent/US10122326B2 ## CPC - H03F 1/56: Modifications of input or output impedances, not otherwise provided for - H03F 1/0272: {by using a signal derived from the output signal} - H03F 3/189: High-frequency amplifiers, e.g. radio frequency amplifiers - H03F 3/193: with field-effect devices (H03F3/195 takes precedence) - H03F 3/21: with semiconductor devices only {(H03F3/245 takes precedence)} - H03F 3/24: of transmitter output stages - H03F 3/245: {with semiconductor devices only} - H04B 1/0458: {Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages (matching circuits in general H03H)} - H03F 2200/102: A non-specified detector of a signal envelope being used in an amplifying circuit - H03F 2200/171: A filter circuit coupled to the output of an amplifier - H03F 2200/387: A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier - H03F 2200/451: the amplifier being a radio frequency amplifier - H03F 2200/78: A comparator being used in a controlling circuit of an amplifier - H03F: AMPLIFIERS - H04B: TRANSMISSION ## Abstract A circuit including: a power amplifier configured to provide amplified signals to a load; an impedance matching network disposed between the power amplifier and the load, the impedance matching network comprising an adjustable impedance unit; and a feedback loop comprising a rectifier, the rectifier being coupled with an output of the power amplifier, the feedback loop further comprising and impedance control circuit configured to receive a signal from the rectifier and to control the adjustable impedance unit in response to the signal from the rectifier. ## Claims ### Claim 1 A circuit comprising: a power amplifier configured to provide amplified signals to a load; an impedance matching network disposed between the power amplifier and the load, the impedance matching network comprising an adjustable impedance unit; and a feedback loop comprising a rectifier, the rectifier being coupled with an output of the power amplifier, the feedback loop further comprising an impedance control circuit configured to receive a signal from the rectifier and to control the adjustable impedance unit in response to the signal from the rectifier, wherein the impedance control circuit comprises a weighting block configured to receive a rectified load voltage, and configured to generate a control signal for the adjustable impedance unit that is a function of the signal from the rectifier and the rectified load voltage. ### Claim 2 (depends on 1) The circuit of claim 1, wherein the impedance control circuit comprises a comparator, wherein the comparator is configured to receive a reference voltage corresponding to a voltage swing level at the output of the power amplifier and configured to receive the signal from the rectifier. ### Claim 3 (depends on 1) The circuit of claim 1, wherein the adjustable impedance unit comprises a variable capacitor coupled with the impedance control circuit. ### Claim 4 (depends on 3) The circuit of claim 3, wherein the variable capacitor comprises one of a diode having a voltage-dependent capacitance or a trans-cap. ### Claim 5 (depends on 1) The circuit of claim 1, wherein the power amplifier is configured to provide an amplified radio frequency (RF) signal to the load. ### Claim 6 (depends on 1) The circuit of claim 1, wherein the signal from the rectifier comprises one of a voltage signal or a current signal. ### Claim 7 (depends on 1) The circuit of claim 1, wherein the power amplifier comprises a metal oxide semiconductor (MOS) transistor, and wherein the impedance matching network is coupled with a drain of the MOS transistor. ### Claim 8 (depends on 1) The circuit of claim 1, wherein a voltage at the output of the power amplifier comprises a differential voltage. ### Claim 9 (depends on 1) The circuit of claim 1, wherein the load comprises an antenna. ### Claim 10 A method performed at a radio frequency (RF) power amplifier (PA) system, the method comprising: sampling a voltage swing at an output terminal of the PA, wherein the PA provides an amplified RF signal to a load; generating a first control signal in response to the voltage swing; applying the first control signal to a comparator to generate a second control signal, wherein the comparator receives a reference signal corresponding to a voltage swing threshold; and adjusting an impedance of a matching network of the PA in response to the second control signal, wherein generating the first control signal comprises: receiving a first rectified voltage from a first rectifier sampling the voltage swing; receiving a second rectified voltage from a second rectifier sampling a voltage at the load; and generating the first control signal as a function of the first rectified voltage and the second rectified voltage. ### Claim 11 (depends on 10) The method of claim 10, wherein generating a first control signal comprises: rectifying a voltage signal from the output terminal of the PA. ### Claim 12 (depends on 10) The method of claim 10, wherein adjusting the impedance of the matching network comprises: biasing a variable capacitor of the matching network in response to the second control signal. ### Claim 13 (depends on 10) The method of claim 10, wherein sampling a voltage swing comprises: sampling a differential voltage at the output terminal of the PA. ### Claim 14 (depends on 10) The method of claim 10, further comprising: receiving an RF signal at an input of the PA; amplifying the RF signal by the PA; and providing an amplified RF signal from the output terminal of the PA to the load. ### Claim 15 A method performed in a radio frequency (RF) circuit having a power amplifier (PA), the method comprising: providing an amplified RF signal from an output terminal of the PA to a load; demodulating the amplified RF signal to generate an envelope signal; processing the envelope signal to generate a control signal that is a function of the envelope signal; and applying the control signal as a bias to an adjustable impedance element of a matching network, wherein the matching network is coupled between the output terminal of the PA and the load, further comprising applying a low pass filter to the control signal before applying the control signal as the bias to the adjustable impedance element.