# US 2020/0401174 A1 · Circuit and method for generating a reference voltage with a voltage regulator and a sample and hold circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0401174 A1 - Document ID: US20200401174A1 - Status: Published application - Kind: A1 - Application number: 16/918,051 - Filed: 2020-07-01 - Published: 2020-12-24 - Earliest claimed: 2016-08-26 - Assignees: Texas Instruments Incorporated - Applicants: Texas Instruments Incorporated - Inventors: James Murdock; Danielle Griffith; Per Torstein Roine - Web page: https://patentgrep.com/patent/US20200401174A1 ## CPC - G05F 1/575: characterised by the feedback circuit - G11C 5/147: {Voltage reference generators, voltage or current regulators; Internally lowered supply levels; Compensation for voltage drops (G11C5/141 takes precedence)} - G11C 27/02: Sample-and-hold arrangements (G11C27/04 takes precedence) - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES - G11C: STATIC STORES (semiconductor memory devices H10B) ## Abstract A reference generator provides a reference output voltage that is continuously available while providing certain efficiencies of a duty-cycled voltage regulator. The reference output voltage is generated by a sample-and-hold circuit that is coupled to a voltage regulator. On command, the sample-and-hold circuit samples a low dropout voltage regulator that may be referenced by a bandgap circuit. During hold periods of the sample-and-hold circuit, the voltage regulator, in particular the bandgap circuit, may be disabled in order to conserve power. A sample cycle by the sample-and-hold circuit may be triggered by a signal received from a configurable finite state machine. The reference generator is effectively duty cycled in a manner that conserves available battery power, while still providing a constant reference output that is always available. The reference generator is especially suited for low-power, battery operated applications. ## Claims ### Claim 1 A circuit comprising: a voltage regulator operable to: receive a supply voltage; and provide a first output voltage; a sample-and-hold circuit coupled to the voltage regulator and operable to: receive the first output voltage and a refresh signal; sample the first output voltage in response to the refresh signal; and provide a second output voltage based on the sampled first output voltage; and a control circuit coupled to the voltage regulator and to the sample-and-hold circuit and operable to provide an enable signal to the voltage regulator, wherein the enable signal is configured such that a portion of the voltage regulator is enabled based on a transmit capability of a sensor being enabled and disabled based on the transmit capability of the sensor being disabled. ### Claim 2 (depends on 1) The circuit of claim 1, wherein the portion of the voltage regulator that is enabled based on the transmit capability of the sensor being enabled and disabled based on the transmit capability of the sensor being disabled includes a bandgap reference circuit. ### Claim 3 (depends on 1) The circuit of claim 1, wherein the voltage regulator includes: a bandgap reference circuit operable to receive the supply voltage and generate a bandgap reference voltage based on the supply voltage; and a low drop out regulator operable to: receive the supply voltage and the bandgap reference voltage; and provide the first output voltage based on the supply voltage and the bandgap reference voltage. ### Claim 4 (depends on 3) The circuit of claim 3, wherein: the low drop out regulator includes: a feedback network coupled to receive the first output voltage and provide a feedback voltage; and an error amplifier operable to compare the feedback voltage and the bandgap reference voltage to determine an error signal; and the low drop out regulator is operable to adjust the first output voltage based on the error signal. ### Claim 5 (depends on 3) The circuit of claim 3, wherein the low drop out regulator circuit includes a pass element operable to provide the first output voltage based on the supply voltage and the bandgap reference voltage. ### Claim 6 (depends on 5) The circuit of claim 5, wherein the pass element includes a bipolar transistor. ### Claim 7 (depends on 1) The circuit of claim 1, wherein the control circuit is operable to generate the enable signal to enable the portion of the voltage regulator prior to causing the refresh signal to cause the sample-and-hold circuit to sample the first output voltage. ### Claim 8 (depends on 1) The circuit of claim 1, wherein the control circuit is operable to generate the enable signal to disable the portion of the voltage regulator after the sample-and-hold circuit has sampled and locked the first output voltage. ### Claim 9 (depends on 1) The circuit of claim 1, wherein the control circuit is operable to generate the refresh signal to have a period based on a hold time of the sample-and-hold circuit. ### Claim 10 A system comprising: a sensor operable to transmit sensed data, wherein the sensor is operable to have a first period where transmission of the sensed data is enabled and a second period where transmission of the sensed data is disabled; a voltage regulator operable to: receive a supply voltage; and provide a first output voltage; a sample-and-hold circuit coupled to the voltage regulator and operable to: provide a second output voltage based on the first output voltage; and a control circuit coupled to the voltage regulator and to the sample-and-hold circuit and operable to provide an enable signal to the voltage regulator, wherein the enable signal is configured such that a portion of the voltage regulator is enabled during the first period where transmission of the sensed data is enabled and disabled during the second period where transmission of the sensed data is disabled. ### Claim 11 (depends on 10) The system of claim 10, wherein the portion of the voltage regulator that is enabled during the first period and disabled during the second period includes a bandgap reference circuit. ### Claim 12 (depends on 11) The system of claim 11, wherein: the bandgap reference circuit is operable to receive the supply voltage and generate a bandgap reference voltage based on the supply voltage; and the voltage regulator includes a low drop out regulator operable to: receive the supply voltage and the bandgap reference voltage; and provide the first output voltage based on the supply voltage and the bandgap reference voltage. ### Claim 13 (depends on 12) The system of claim 12, wherein: the low drop out regulator includes: a feedback network coupled to receive the first output voltage and provide a feedback voltage; and an error amplifier operable to compare the feedback voltage and the bandgap reference voltage to determine an error signal; and the low drop out regulator is operable to adjust the first output voltage based on the error signal. ### Claim 14 (depends on 12) The system of claim 12, wherein the low drop out regulator includes a pass element operable to provide the first output voltage based on the supply voltage and the bandgap reference voltage. ### Claim 15 (depends on 14) The system of claim 14, wherein the pass element includes a bipolar transistor. ### Claim 16 (depends on 10) The system of claim 10, wherein the control circuit is operable to generate the enable signal to enable the portion of the voltage regulator prior to causing the sample-and-hold circuit to sample the first output voltage. ### Claim 17 (depends on 10) The system of claim 10, wherein the control circuit is operable to generate the enable signal to disable the portion of the voltage regulator after the sample-and-hold circuit has sampled and locked the first output voltage. ### Claim 18 A method comprising: receiving, by a voltage regulator, a supply voltage; providing, by the voltage regulator, a first output voltage based on the supply voltage; sampling, by a sample-and-hold circuit, the first output voltage to provide a second output voltage; and disabling a portion of the voltage regulator based on a transmit duty cycle of a sensor such that the voltage regulator is disabled when a transmit capability of the sensor is disabled. ### Claim 19 (depends on 18) The method of claim 18, wherein the portion of the voltage regulator includes a bandgap reference circuit. ### Claim 20 (depends on 18) The method of claim 18 further comprising enabling the portion of the voltage regulator prior to the sampling of the first output voltage by the sample-and-hold circuit.