# US 8,542,052 B2 · Integrated circuit capacitor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,052 B2 - Document ID: US8542052B2 - Status: Granted - Kind: B2 - Application number: 13/287,449 - Filed: 2011-11-02 - Published: 2012-05-03 - Granted: 2013-09-24 - Earliest claimed: 2010-11-03 - Assignees: NXP B.V. - Applicants: Hans Halberstadt - Inventors: Hans Halberstadt - Web page: https://patentgrep.com/patent/US8542052B2 ## CPC - H03H 11/405: {Positive impedance converters (H03H11/42 takes precedence; used in frequency selective networks H03H11/0416)} - H03H 11/481: {Simulating capacitances} - H03H 11/483: {Simulating capacitance multipliers} - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) ## Abstract An electrical circuit for emulating a capacitance, comprises a physical capacitor which is charged by charge flow from the input of the electrical circuit. An amplifier amplifies the voltage at the input of the electrical circuit such that the physical capacitor is charged with a larger change in voltage than the change in voltage at the input. This implements an effective multiplication of capacitance. A reset system resets the physical capacitor without drawing charge from the input of the electrical circuit. This extends the voltages which can be provided to the input. ## Claims ### Claim 1 An electrical circuit for emulating a capacitance, comprising; a physical capacitor which is charged by charge flow from an input of the electrical circuit; an amplifier for amplifying the voltage at the input of the electrical circuit such that the physical capacitor is charged with a larger change in voltage than a change in voltage at the input; and a reset system for resetting a state of charge of the physical capacitor without drawing charge from the input of the electrical circuit; wherein the amplifier and the physical capacitor form an amplifying integrator circuit, wherein the physical capacitor is in a first feedback path between an output of the amplifier and a first input of the amplifier with the input of the electrical circuit provided to the first input of the amplifier, wherein the electrical circuit further comprises a gain element in a second feedback path between the output of the amplifier and a second input of the amplifier, and wherein the reset system comprises: a control circuit for controlling the second feedback path in dependence on a voltage at the input of the electrical circuit, wherein the control circuit comprises a circuit for controlling one of a current and a voltage provided to the gain element; an up/down counter that counts up when the voltage at the output of the amplifier reaches a first level compared to the input and counts down when the voltage at the output of the amplifier reaches a second level compared to the input; and a D/A converter that converts the output of the up/down counter to an analogue signal, wherein the analogue signal is applied to an input of the gain element. ### Claim 2 (depends on 1) A circuit as claimed in claim 1, wherein the D/A converter has a voltage output. ### Claim 3 (depends on 1) A circuit as claimed in claim 1, wherein the D/A converter has a current output. ### Claim 4 (depends on 1) A circuit as claimed in claim 1, wherein the physical capacitor has a programmable value of capacitance. ### Claim 5 (depends on 1) A circuit as claimed in claim 1, wherein the gain element has a programmable gain value. ### Claim 6 (depends on 1) A circuit as claimed in claim 1, wherein the circuit has first and second inputs between which a floating capacitor is defined. ### Claim 7 (depends on 6) A circuit according to claim 6, where the input current to one of the inputs is copied to the other input. ### Claim 8 (depends on 1) An integrated circuit including a circuit according claim 1. ### Claim 9 A method of emulating a capacitance using an electrical circuit, comprising: charging a physical capacitor by a charge flow from an input of the electrical circuit; amplifying a voltage at the input of the electrical circuit such that the physical capacitor is changed with a larger change in voltage than a change in voltage at the input; resetting a state of charge of the physical capacitor without drawing charge from the input of the electrical circuit in response to the voltage at the input of the electrical circuit reaching a threshold; integrating and amplifying the charge flow to the physical capacitor by connecting the physical capacitor in a first feedback path directly between an amplifier output and a first input of the amplifier to which the input of the electrical circuit is connected, and the resetting comprises: controlling a second feedback path between the amplifier output and a second input of the amplifier, which second feedback path includes a gain element, the configuration being in dependence on a voltage at the input of the electrical circuit; and wherein controlling the second feedback path comprises: counting up at an up/down counter when the voltage at the output of the amplifier reaches a first level compared to the input and counting down at the up/down counter when the voltage at the output of the amplifier reaches a second level compared to the input; and converting the output of the up/down counter to an analogue signal, wherein the analogue signal is applied to an input of the gain element. ### Claim 10 (depends on 1) The circuit of claim 1, wherein the reset system comprises a control circuit for controlling, a feedback path having a gain element between an output of the amplifier and an input of the amplifier, in dependence on a voltage at the input of the electrical circuit, wherein the control circuit comprises: a circuit for controlling one of a current and a voltage provided to the gain element; an up/down counter that counts up when the voltage at the output of the amplifier reaches a first level compared to the input and counts down when the voltage at the output of the amplifier reaches a second level compared to the input; and a D/A converter that converts the output of the up/down counter to an analogue signal, wherein the analogue signal is applied to an input of the gain element.