# US 2020/0403579 A1 · Variable gain amplifier device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0403579 A1 - Document ID: US20200403579A1 - Status: Published application - Kind: A1 - Application number: 16/804,139 - Filed: 2020-02-28 - Published: 2020-12-24 - Earliest claimed: 2019-06-20 - Assignees: Realtek Semiconductor Corp. - Applicants: Realtek Semiconductor Corporation - Inventors: Yi-Chun HSIEH - Web page: https://patentgrep.com/patent/US20200403579A1 ## CPC - H03F 1/30: Modifications of amplifiers to reduce influence of variations of temperature or supply voltage {or other physical parameters (in differential amplifiers H03F3/45479)} - H03G 1/0029: {using field-effect transistors [FET]} - H03F 3/04: with semiconductor devices only - H03F 3/45197: {Pl types (H03F3/45224, H03F3/45251 take precedence)} - H03G 3/30: in amplifiers having semiconductor devices - H03F 2200/447: the amplifier being protected to temperature influence - H03F 2203/45492: the CSC being a pi circuit and the resistor being implemented by one or more controlled transistors - H03G 2201/103: being an amplifying element - H03G 2201/708: being temperature - H03F: AMPLIFIERS - H03G: CONTROL OF AMPLIFICATION ## Abstract A variable gain amplifier device includes a variable gain amplifier circuitry and a control voltage generating circuitry. The variable gain amplifier circuitry is configured to amplify input signals to generate output signals, wherein the variable gain amplifier circuitry includes a gain setting circuit that is configured to set a gain of the variable gain amplifier circuitry according to a control voltage. The control voltage generation circuitry is configured to simulate at least one circuit portion of the variable gain amplifier circuitry, in order to generate the control voltage according to the input signals and a setting voltage. ## Claims ### Claim 1 A variable gain amplifier device comprising: a variable gain amplifier circuitry configured to amplify input signals to generate a plurality of output signals, wherein the variable gain amplifier circuitry comprises a gain setting circuit that is configured to set a gain of the variable gain amplifier circuitry according to a control voltage; and a control voltage generation circuitry configured to simulate at least one circuit portion of the variable gain amplifier circuitry, in order to generate the control voltage according to the input signals and a setting voltage. ### Claim 2 (depends on 1) The variable gain amplifier device of claim 1, wherein the control voltage generation circuitry is further configured to generate the control voltage according to the input signals, the setting voltage, and at least one node voltage, wherein the at least one node voltage is outputted from at least one node in the at least one circuit portion. ### Claim 3 (depends on 2) The variable gain amplifier device of claim 2, wherein the at least one circuit portion comprises the gain setting circuit, and the gain setting circuit is coupled to the at least one node. ### Claim 4 (depends on 1) The variable gain amplifier device of claim 1, wherein the control voltage generation circuitry comprises: a simulation circuit configured to simulate the at least one circuit portion, and configured to generate a first voltage according to a first reference signal; and a feedback control circuit coupled to the simulation circuit, and configured to generate the control voltage according to a second reference signal and the first voltage. ### Claim 5 (depends on 4) The variable gain amplifier device of claim 4, wherein the first reference signal is generated according to the input signals and the setting voltage. ### Claim 6 (depends on 5) The variable gain amplifier device of claim 5, wherein the first reference signal is the sum of the setting voltage and an average value of the input signals. ### Claim 7 (depends on 4) The variable gain amplifier device of claim 4, wherein the second reference signal is generated according to the setting voltage and at least one node voltage associated with the at least one circuit portion. ### Claim 8 (depends on 7) The variable gain amplifier device of claim 7, wherein the second reference signal is the difference of the setting voltage and an average value of the at least one node voltage. ### Claim 9 (depends on 1) The variable gain amplifier device of claim 1, wherein the gain setting circuit is configured to provide an equivalent resistance to set the gain, and the equivalent resistance is determined according to twice the setting voltage. ### Claim 10 A variable gain amplifier device comprising: a plurality of first transistors configured to generate a first output signal and a second output signal according to a first input signal and a second input signal; a second transistor coupled to the first transistors at a first node and a second node, wherein the second transistor is configured to receive a control voltage to set a gain; a third transistor configured to receive a first reference signal; a fourth transistor, wherein a first terminal of the fourth transistor is coupled to the third transistor; and an amplifier, wherein a first input terminal of the amplifier is configured to receive a second reference signal, a second input terminal of the amplifier is coupled to a second terminal of the fourth transistor, and an output terminal of the amplifier is coupled to a control terminal of the fourth transistor and configured to output the control voltage. ### Claim 11 (depends on 10) The variable gain amplifier device of claim 10, wherein an equivalent resistance of the third transistor is determined according to twice the setting voltage. ### Claim 12 (depends on 10) The variable gain amplifier device of claim 10, wherein the first reference signal is generated according to the input signals and a setting voltage. ### Claim 13 (depends on 12) The variable gain amplifier device of claim 12, wherein the first reference signal is the sum of the setting voltage and an average value of the input signals. ### Claim 14 (depends on 10) The variable gain amplifier device of claim 10, wherein the second reference signal is generated according to a first node voltage on the first node, a second node voltage on the second node, and a setting voltage. ### Claim 15 (depends on 14) The variable gain amplifier device of claim 14, wherein the second reference signal is the difference of the setting voltage and an average value of the at least one node voltage. ### Claim 16 (depends on 10) The variable gain amplifier device of claim 10, wherein a connection of the third transistor and the fourth transistor is set to be the same as a connection of one of the first transistors and the second transistor.