# US 9,438,192 B2 · Capacitive programmable gain amplifier > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,438,192 B2 - Document ID: US9438192B2 - Status: Granted - Kind: B2 - Application number: 14/242,285 - Filed: 2014-04-01 - Published: 2015-10-01 - Granted: 2016-09-06 - Earliest claimed: 2014-04-01 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Wenchang Huang; Peter Jivan Shah; Meysam Azin; Arash Mehrabi - Web page: https://patentgrep.com/patent/US9438192B2 ## CPC - H03G 3/008: {Control by switched capacitors} - H03F 3/45475: {using IC blocks as the active amplifying circuit} - H03G 1/0088: {using discontinuously variable devices, e.g. switch-operated} - H03G 3/001: {Digital control of analog signals} - H03F 2200/129: there being a feedback over the complete amplifier - H03F 2200/267: A capacitor based passive circuit, e.g. filter, being used in an amplifying circuit - H03F 2203/45118: At least one reactive element being added to at least one feedback circuit of a dif amp - H03F 2203/45156: At least one capacitor being added at the input of a dif amp - H03F 2203/45514: the FBC comprising one or more switched capacitors, and being coupled between the LC and the IC - H03G: CONTROL OF AMPLIFICATION - H03F: AMPLIFIERS ## Abstract An apparatus includes an operational amplifier and a plurality of capacitors coupled to an input terminal of the operational amplifier and configured to be selectively coupled to receive one of an input voltage signal and an output voltage signal of the operational amplifier. ## Claims ### Claim 1 An apparatus comprising: an operational amplifier; a plurality of capacitors coupled to an input terminal of the operational amplifier, the plurality of capacitors comprising a first capacitor and a second capacitor; a first switch coupled to the first capacitor, the first switch configured to selectively couple the first capacitor to receive an input voltage signal of the operational amplifier or to receive an output voltage signal of the operational amplifier; and a second switch coupled to the second capacitor, the second switch configured to selectively couple the second capacitor to receive the input voltage signal or to receive the output voltage signal, wherein selectively coupling the second capacitor to receive the input voltage signal or to receive the output voltage signal occurs independently of the coupling of the first capacitor to receive the input voltage signal or to receive the output voltage signal. ### Claim 2 (depends on 1) The apparatus of claim 1, further comprising a plurality of switches configured to couple a corresponding capacitor of the plurality of capacitors to a first terminal to receive the input voltage signal or to a second terminal to receive the output voltage signal, the plurality of switches includes the first switch and the second switch. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the input terminal of the operational amplifier is a virtual ground node. ### Claim 4 (depends on 1) The apparatus of claim 1, further comprising: an input capacitor coupled to receive the input voltage signal and coupled to the input terminal of the operational amplifier; and a feedback capacitor coupled to receive the output voltage signal of the operational amplifier and coupled to the input terminal of the operational amplifier. ### Claim 5 (depends on 4) The apparatus of claim 4, wherein the input capacitor, the feedback capacitor, the plurality of capacitors, and the operational amplifier are included in a capacitive programmable gain amplifier. ### Claim 6 (depends on 4) The apparatus of claim 4, further comprising: a second input capacitor coupled to receive a second input voltage signal and coupled to a second input terminal of the operational amplifier; a second feedback capacitor coupled to receive a second output voltage signal of the operational amplifier and coupled to the second input terminal of the operational amplifier; and a second plurality of capacitors coupled to the second input terminal of the operational amplifier and configured to be selectively coupled to receive at least one of the second input voltage signal and the second output voltage signal, or a combination thereof. ### Claim 7 (depends on 6) The apparatus of claim 6, wherein input voltage signal and the second input voltage signal are differential signals, and wherein the output voltage signal and the second output voltage signal are differential signals. ### Claim 8 (depends on 6) The apparatus of claim 6, further comprising a second plurality of switches configured to couple a corresponding capacitor of the second plurality of capacitors to receive the second input voltage signal or to receive the second output voltage signal. ### Claim 9 (depends on 8) The apparatus of claim 8, wherein the second plurality of switches are coupled to a first terminal of the corresponding capacitor and selectively coupled to one of a third terminal to receive the second input voltage signal and a fourth terminal to receive the second output voltage signal, and wherein a second terminal of the corresponding capacitor is coupled to a virtual ground node. ### Claim 10 A method comprising: selectively coupling a first capacitor of a plurality of capacitors to receive an input voltage signal of a capacitive programmable gain amplifier including an operational amplifier to increase a gain of the capacitive programmable gain amplifier; selectively coupling the first capacitor of the plurality of capacitors to receive an output voltage signal of the operational amplifier to decrease the gain of the capacitive programmable gain amplifier; selectively coupling a second capacitor of the plurality of capacitors to receive the input voltage signal to increase the gain of the capacitive programmable gain amplifier; and selectively coupling the second capacitor of the plurality of capacitors to receive the output voltage signal to decrease the gain of the capacitive programmable gain amplifier, wherein selectively coupling the second capacitor of the plurality of capacitors to receive the input voltage signal or the output voltage signal occurs independently of the coupling of the first capacitor to receive the input voltage signal or the output voltage signal. ### Claim 11 (depends on 10) The method of claim 10, wherein the first capacitor of the plurality of capacitors is selectively coupled to receive the input voltage signal or to receive the output voltage signal via a switch. ### Claim 12 (depends on 11) The method of claim 11, wherein the switch is coupled to a first terminal of the first capacitor of the plurality of capacitors and selectively coupled to a first terminal to receive the input voltage signal or to a second terminal to receive the output voltage signal, and wherein a second terminal of the first capacitor is coupled to a virtual ground node. ### Claim 13 An apparatus comprising: means for selectively coupling a first capacitor of a plurality of capacitors to receive an input voltage signal of an operational amplifier or to receive an output voltage signal of the operational amplifier; and means for selectively coupling a second capacitor of the plurality of capacitors to receive the input voltage signal or to receive the output voltage signal, wherein selectively coupling the second capacitor to receive the input voltage signal or to receive the output voltage signal occurs independently of the coupling of the first capacitor to receive the input voltage signal or to receive the output voltage signal. ### Claim 14 (depends on 13) The apparatus of claim 13, wherein a terminal of the first capacitor is coupled to a means for providing an input signal and a second terminal of the first capacitor is coupled to a virtual ground node. ### Claim 15 (depends on 14) The apparatus of claim 14, wherein the means for selectively coupling the second capacitor is selectively coupled to a first input terminal or to a second input terminal of the operational amplifier, and wherein the second capacitor is coupled to a virtual ground node. ### Claim 16 (depends on 13) The apparatus of claim 13, wherein the first capacitor is coupled to an amplifier input terminal of the operational amplifier. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the amplifier input terminal of the operational amplifier is a virtual ground node. ### Claim 18 (depends on 13) The apparatus of claim 13, wherein the second capacitor is coupled to an amplifier input terminal of the operational amplifier. ### Claim 19 (depends on 1) The apparatus of claim 1, wherein the first switch is configured to couple the first capacitor to the input voltage signal and the second switch is configured to couple the second capacitor to the output voltage signal while the first capacitor is coupled to the input voltage signal. ### Claim 20 (depends on 1) The apparatus of claim 1, wherein the second capacitor is configurable to receive the input voltage signal or the output voltage signal via the second switch independently of the first capacitor being configured to receive the input voltage signal or the output voltage signal via the first switch. ### Claim 21 An apparatus comprising: an operational amplifier; a first switch coupled to a first capacitor, the first switch configured to selectively couple a first terminal of the first capacitor to receive an input voltage signal of the operational amplifier or to receive an output voltage signal of the operational amplifier, wherein a second terminal of the first capacitor is non-selectively coupled to an input terminal of the operational amplifier; and a second switch coupled to a second capacitor, the second switch configured to selectively couple a first terminal of the second capacitor to receive the input voltage signal or to receive the output voltage signal, wherein a second terminal of the second capacitor is non-selectively coupled to the input terminal of the operation amplifier.