# US 9,436,197 B1 · Adaptive opamp compensation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,436,197 B1 - Document ID: US9436197B1 - Status: Granted - Kind: B1 - Application number: 13/857,662 - Filed: 2013-04-05 - Granted: 2016-09-06 - Earliest claimed: 2012-04-06 - Assignees: Marvell International Ltd. - Applicants: Marvell International Ltd. - Inventors: Qiang Tang; Chen Ma; Bo Wang - Web page: https://patentgrep.com/patent/US9436197B1 ## CPC - G05F 1/565: sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor (G05F1/563 takes precedence) - G05F 1/575: characterised by the feedback circuit - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES ## Abstract Aspects of the disclosure provide a circuit having an amplifier and a load current based control circuit. The amplifier is configured to detect a difference between a feedback voltage and a reference voltage, and control, based on the difference, a pass device to regulate an output voltage for supplying power to load devices. The feedback voltage is indicative of the regulated output voltage from the pass device. The load current based control circuit is configured to sense a load current output from the pass device to the load devices and generate a control signal to adjust a compensation capacitance based on the sensed load current to adjust a zero frequency of the circuit. ## Claims ### Claim 1 A circuit, comprising: an amplifier configured to detect a difference between a feedback voltage and a reference voltage, and control, based on the difference, a pass device to regulate an output voltage for supplying power to load devices, the feedback voltage being indicative of the regulated output voltage from the pass device; and a load current based control circuit configured to sense a load current output from the pass device to the load devices and generate a control signal to adjust a compensation capacitance of a variable capacitor based on the sensed load current to adjust a zero frequency of the circuit, a first terminal of the variable capacitor being directly coupled to one of inputs of the amplifier and a second terminal of the variable capacitor being coupled directly to the pass device. ### Claim 2 (depends on 1) The circuit of claim 1, wherein the load current based control circuit is coupled with the amplifier and the pass device into a compensation loop to sense the load current and adaptively adjust the compensation capacitance. ### Claim 3 (depends on 2) The circuit of claim 2, wherein the load current based control circuit comprises: a low pass filter configured to filter the control signal and shape a bandwidth of the compensation loop. ### Claim 4 (depends on 1) The circuit of claim 1, wherein the load current based control circuit is configured to reduce the compensation capacitance when the load current increases. ### Claim 5 (depends on 1) The circuit of claim 1, wherein the load current based control circuit is configured to adjust a capacitance of the variable capacitor that is a varactor formed of transistors. ### Claim 6 (depends on 1) The circuit of claim 1, wherein the load current based control circuit is configured to increase the zero frequency of the circuit when the load current increases. ### Claim 7 (depends on 1) The circuit of claim 1, wherein the load current based control circuit is configured to increase the zero frequency of the circuit when a pole frequency of the amplifier is dominant. ### Claim 8 A method comprising: controlling, in a voltage regulator circuit, a pass device to regulate an output voltage for supplying power to load devices by an amplifier; sensing a load current output from the pass device to the load devices; and generating a control signal to adjust a compensation capacitance of a variable capacitor based on the sensed load current to adjust a zero frequency of the voltage regulator circuit, a first terminal of the variable capacitor being directly coupled to one of inputs of the amplifier and a second terminal of the variable capacitor being coupled directly to the pass device. ### Claim 9 (depends on 8) The method of claim 8, wherein generating the control signal to adjust the compensation capacitance based on the sensed load current to adjust the zero frequency of the voltage regulator circuit comprises: forming a compensation loop to sense the load current and adaptively adjust the compensation capacitance. ### Claim 10 (depends on 9) The method of claim 9, further comprising: low-pass filtering the control signal to shape a bandwidth of the compensation loop. ### Claim 11 (depends on 8) The method of claim 8, wherein generating the control signal to adjust the compensation capacitance based on the sensed load current to adjust the zero frequency of the voltage regulator circuit comprises: reducing the compensation capacitance when the load current increases. ### Claim 12 (depends on 8) The method of claim 8, wherein generating the control signal to adjust the compensation capacitance based on the sensed load current to adjust the zero frequency of the voltage regulator circuit comprises: adjusting a capacitance of the variable capacitor that is a varactor formed of transistors. ### Claim 13 (depends on 8) The method of claim 8, wherein generating the control signal to adjust the compensation capacitance based on the sensed load current to adjust the zero frequency of the voltage regulator circuit comprises: increasing the zero frequency of the voltage regulator circuit when the load current increases. ### Claim 14 A voltage regulator, comprising: a pass device configured to generate an output voltage for supplying power to load devices based on an unregulated power supply; a feedback circuit configured to generate a feedback voltage indicative of the output voltage; an amplifier configured to detect a difference between the feedback voltage and a reference voltage, and control, based on the difference, the pass device to regulate the output voltage; a compensation capacitor circuit configured to provide a zero frequency for the voltage regulator; and a load current based control circuit configured to sense a load current output from the pass device to the load devices and generate a control signal to adjust a compensation capacitance of the compensation capacitor circuit based on the sensed load current to adjust the zero frequency of the voltage regulator, a first terminal of the compensation capacitor being directly coupled to one of inputs of the amplifier and a second terminal of the compensation capacitor being coupled directly to the pass device. ### Claim 15 (depends on 14) The voltage regulator of claim 14, wherein the load current based control circuit is coupled with the compensation capacitor circuit, the amplifier and the pass device into a compensation loop to sense the load current and adaptively adjust the compensation capacitance. ### Claim 16 (depends on 15) The voltage regulator of claim 15, wherein the load current based control circuit comprises: a low pass filter configured to filter the control signal and shape a bandwidth of the compensation loop. ### Claim 17 (depends on 14) The voltage regulator of claim 14, wherein the load current based control circuit is configured to reduce the compensation capacitance when the load current increases. ### Claim 18 (depends on 14) The voltage regulator of claim 14, wherein the compensation capacitor circuit is a varactor formed of transistors. ### Claim 19 (depends on 14) The voltage regulator of claim 14, wherein the load current based control circuit is configured to increase the zero frequency of the circuit when the load current increases. ### Claim 20 (depends on 14) The voltage regulator of claim 14, wherein the load current based control circuit is configured to increase the zero frequency of the circuit when a pole frequency provided by the amplifier is dominant. ### Claim 21 A circuit, comprising: an amplifier configured to detect a difference between a feedback voltage and a reference voltage, and control, based on the difference, a pass device to regulate an output voltage for supplying power to load devices, the feedback voltage being indicative of the regulated output voltage from the pass device; and a load current based control circuit configured to sense a load current output from the pass device to the load devices and generate a control signal to adjust a compensation capacitance of a variable capacitor based on the sensed load current to adjust a zero frequency of the circuit, a first terminal of the variable capacitor being coupled to one of inputs of the amplifier and a second terminal of the variable capacitor being coupled directly to a drain terminal of the pass device.