# US 2018/0323747 A1 · Multi-level digital adaptive pa bias for microwave radios > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0323747 A1 - Document ID: US20180323747A1 - Status: Published application - Kind: A1 - Application number: 15/588,452 - Filed: 2017-05-05 - Published: 2018-11-08 - Earliest claimed: 2017-05-05 - Assignees: Zte Corporation - Applicants: Zte Corporation - Inventors: Andrey KOCHETKOV; Ying SHEN; Shawn WALSH; Thanh NGUYEN; Aleksandr SEMENYSHEV; Zhiping FENG - Web page: https://patentgrep.com/patent/US20180323747A1 ## CPC - H03F 1/0205: {in transistor amplifiers} - H03F 1/0266: {by using a signal derived from the input signal} - H03F 3/195: in integrated circuits - H03F 3/245: {with semiconductor devices only} - H03F 2200/102: A non-specified detector of a signal envelope being used in an amplifying circuit - H03F 2200/252: Multiple switches coupled in the input circuit of an amplifier are controlled by a circuit, e.g. feedback circuitry being controlling the switch - H03F 2200/451: the amplifier being a radio frequency amplifier - H03F: AMPLIFIERS ## Abstract A method for biasing a power amplifier using a transmission signal having a time-varying envelope is provided. The method comprises producing a time-varying signal indicative of an amplitude of the envelope of the transmission signal and comparing the time-varying signal to a plurality of distinct threshold voltages. The method further comprises, for each of the plurality of distinct threshold voltages exceeded by the time-varying signal, providing a respective bias voltage to a respective input of a summing device and producing, using the summing device, an output bias voltage that is at least a sum of the respective bias voltages provided to the respective inputs of the summing device. The method further comprises biasing the power amplifier with the output bias voltage and amplifying the transmission signal using the power amplifier biased at the output bias voltage. ## Claims ### Claim 1 A power amplifier circuit, comprising: a power amplifier for amplifying a transmission signal, the transmission signal having a time-varying envelope; an envelope detector that produces a time-varying signal indicative of an amplitude of the envelope of the transmission signal; a plurality of comparators for comparing the time-varying signal to a plurality of distinct threshold voltages, each comparator having a first input receiving the time-varying signal and a second input receiving a respective threshold voltage of the plurality of distinct threshold voltages; a plurality of switches, each switch having a first terminal and a second terminal, each switch being controlled by an output of a respective comparator of the plurality of comparators to form a conductive channel between the first terminal and the second terminal when the time-varying signal indicative of the amplitude of the envelope of the transmission signal exceeds the respective threshold voltage for the respective comparator; a plurality of digital-to-analog converters (DACs) providing a plurality of bias voltages, wherein the first terminal of each switch of the plurality of switches is coupled to a respective DAC of the plurality of DACs; a summing device having inputs coupled to the second terminals of each of the plurality of switches to produce an output bias voltage that is at least a sum of bias voltages from each of the second terminals of the plurality of switches, wherein the output bias voltage is applied to bias the power amplifier; memory storing a plurality of sets of distinct threshold voltages, each set of the plurality of sets of distinct threshold voltages corresponding to a modulation type; and one or more processors configured to: detect a change in modulation type of the transmission signal; and reprogram the plurality of distinct threshold voltages to a different set of distinct threshold voltages, of the plurality of sets of distinct threshold voltages, based on the change in the modulation type of the transmission signal. ### Claim 2 (depends on 1) The power amplifier circuit of claim 1, wherein the power amplifier amplifies the signal carrying information prior to transmission of the signal by an antenna. ### Claim 3 (canceled) ### Claim 4 (depends on 1) The power amplifier circuit of claim 1, the memory further storing values for the plurality of bias voltages corresponding to the plurality of distinct threshold voltages. ### Claim 5 (canceled) ### Claim 6 (depends on 1) The power amplifier circuit of claim 1, wherein the power amplifier circuit is part of an integrated circuit. ### Claim 7 (depends on 1) The power amplifier circuit of claim 1, wherein the plurality of switches are FETs. ### Claim 8 (depends on 1) The power amplifier circuit of claim 1, wherein the summing device is also coupled to a minimum bias voltage. ### Claim 9 (depends on 1) The power amplifier circuit of claim 1, wherein an operational amplifier amplifies the output from the summing device before applying bias voltage to the power amplifier. ### Claim 10 (depends on 1) The power amplifier circuit of claim 1, further including an up-converter, wherein: the envelope detector is connected to an input port of the up-converter; and an input port of the power amplifier is connected to an output port of the up-converter. ### Claim 11 A method for biasing a power amplifier using a transmission signal having a time-varying envelope comprising: at a power amplifier circuit that includes one or more processors and memory storing a plurality of sets of distinct threshold voltages, each set of the plurality of sets of distinct threshold voltages corresponding to a modulation type: producing a time-varying signal indicative of an amplitude of the envelope of the transmission signal; comparing the time-varying signal to a plurality of distinct threshold voltages; for each of the plurality of distinct threshold voltages exceeded by the time-varying signal, providing a respective bias voltage to a respective input of a summing device; producing, using the summing device, an output bias voltage that is at least a sum of the respective bias voltages provided to the respective inputs of the summing device; biasing the power amplifier with the output bias voltage; amplifying the transmission signal using the power amplifier biased at the output bias voltage; detecting a change in modulation type of the transmission signal; and reprograming the plurality of distinct threshold voltages to a different set of distinct threshold voltages, of the plurality of sets of distinct threshold voltages, in response to the change in the modulation of the transmission signal. ### Claim 12 (depends on 11) The method of claim 11, wherein amplifying the signal carrying information occurs prior to transmission of the signal by an antenna. ### Claim 13 (canceled) ### Claim 14 (depends on 11) The method of claim 11, wherein the memory also stores values for the respective bias voltages. ### Claim 15 (canceled) ### Claim 16 (depends on 11) The method of claim 11, wherein the method is performed within an integrated circuit. ### Claim 17 (depends on 11) The method of claim 11, wherein the summing device is also coupled to a minimum bias voltage. ### Claim 18 (depends on 11) The method of claim 11, further comprising, amplifying the output from the summing device before applying bias voltage to the power amplifier. ### Claim 19 (depends on 11) The method of claim 11, wherein the envelope detector is connected to an input port of an up-converter. ### Claim 20 (depends on 1) The power amplifier circuit of claim 1, wherein the plurality of sets of distinct threshold voltages include a set of distinct threshold voltages corresponding to one or more of the following modulation types: QAM1024, QPSK, QAM4096. ### Claim 21 (depends on 11) The method of claim 11, wherein the plurality of sets of distinct threshold voltages include a set of distinct threshold voltages corresponding to one or more of the following modulation types: QAM1024, QPSK, QAM4096.