# US 2020/0401177 A1 · Automatically controlled bandgap reference circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0401177 A1 - Document ID: US20200401177A1 - Status: Published application - Kind: A1 - Application number: 16/905,019 - Filed: 2020-06-18 - Published: 2020-12-24 - Earliest claimed: 2019-06-19 - Assignees: Skyworks Solutions, Inc. - Applicants: Skyworks Solutions, Inc. - Inventors: Bang Li LIANG - Web page: https://patentgrep.com/patent/US20200401177A1 ## CPC - G05F 3/30: Regulators using the difference between the base-emitter voltages of two bipolar transistors operating at different current densities (G05F3/26 takes precedence) - G05F 1/595: semiconductor devices connected in series - G05F 1/468: {characterised by reference voltage circuitry, e.g. soft start, remote shutdown} - G05F 1/567: for temperature compensation - G05F 3/245: {producing a voltage or current as a predetermined function of the temperature} - H03M 1/001: {Analogue/digital/analogue conversion} - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES - H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C) ## Abstract Circuits, systems, and methods to automatically switch modes to provide constant reference voltages are discussed herein. For example, a bandgap reference system may include a first bandgap reference circuit configured to provide a first bandgap reference voltage, a low dropout regulator coupled to the first bandgap reference circuit, a temperature circuit coupled to the low dropout regulator, and a second bandgap reference circuit coupled to the low dropout regulator and the temperature circuit. The second bandgap reference circuit may be configured to configure one or more impedance elements based at least in part on a temperature signal and provide a second bandgap reference voltage based on one or more currents that pass through the one or more impedance elements. ## Claims ### Claim 1 A bandgap reference system comprising: a first bandgap reference circuit configured to provide a first bandgap reference voltage; a low dropout regulator coupled to the first bandgap reference circuit, the low dropout regulator configured to receive the first bandgap reference voltage and provide a regulated voltage based at least in part on the first bandgap reference voltage; a temperature circuit coupled to the low dropout regulator, the temperature circuit configured to receive the regulated voltage and output a temperature signal indicating a temperature; and a second bandgap reference circuit coupled to the low dropout regulator and the temperature circuit, the second bandgap reference circuit configured to configure one or more impedance elements based at least in part on the temperature signal and provide a second bandgap reference voltage based at least in part on one or more currents that pass through the one or more impedance elements. ### Claim 2 (depends on 1) The bandgap reference system of claim 1 wherein the first bandgap reference circuit is associated with a first amount of reference voltage variation over a temperature range and the second bandgap reference circuit is associated with a second amount of reference voltage variation over the temperature range, the second amount of reference voltage variation being less than the first amount of reference voltage variation. ### Claim 3 (depends on 1) The bandgap reference system of claim 1 wherein the temperature circuit includes a voltage generation circuit configured to generate a Proportional-to-Absolute-Temperature (PTAT) voltage, a slope converter circuit to convert the PTAT voltage, and a voltage follower circuit to output the converted PTAT voltage as the temperature signal. ### Claim 4 (depends on 1) The bandgap reference system of claim 1 further comprising an analog-to-digital converter coupled to the temperature circuit, the analog-to-digital converter configured to receive the temperature signal from the temperature circuit, convert the temperature signal, and provide the converted temperature signal to the second bandgap reference circuit. ### Claim 5 (depends on 1) The bandgap reference system of claim 1 wherein the second bandgap reference circuit includes a current generation circuit configured to generate a Proportional-to-Absolute-Temperature (PTAT) current and provide the PTAT current to a node. ### Claim 6 (depends on 5) The bandgap reference system of claim 5 wherein the second bandgap reference circuit includes an input bandgap circuit coupled to the node, the input bandgap circuit configured to receive an input bandgap reference voltage from the first bandgap reference circuit, convert the input bandgap reference voltage to an input bandgap reference current, and provide a first current to the node based at least in part on the temperature signal, the first current being associated with the input bandgap reference current. ### Claim 7 (depends on 6) The bandgap reference system of claim 6 wherein the one or more currents that pass through the one or more impedance elements include the PTAT current and the first current. ### Claim 8 (depends on 1) The bandgap reference system of claim 1 wherein the second bandgap reference circuit includes one or more transistors coupled to the one or more impedance elements, the second bandgap reference circuit is configured to configure the one or more impedance elements by controlling the one or more transistors based at least in part on the temperature signal. ### Claim 9 (depends on 1) The bandgap reference system of claim 1 wherein the second bandgap reference circuit includes a start-up circuit configured to receive the regulated voltage from the low dropout regulator and power-up the second bandgap reference circuit based at least in part on the regulated voltage. ### Claim 10 A bandgap reference circuit comprising: a current generation circuit to generate a Proportional-to-Absolute-Temperature (PTAT) current and provide the PTAT current to a node; an input bandgap circuit coupled to the node, the input bandgap circuit to receive an input bandgap reference voltage from another bandgap reference circuit and control a first current to the node based at least in part on a temperature signal, the first current being associated with the input bandgap reference voltage; and a reference voltage circuit coupled to the node and including one or more impedance elements, the reference voltage circuit to configure the one or more impedance elements based at least in part on the temperature signal, receive a second current via the node, and provide an output bandgap reference voltage based at least in part on the second current passing through the one or more impedance elements. ### Claim 11 (depends on 10) The bandgap reference circuit of claim 10 wherein the bandgap reference circuit is associated with a first amount of reference voltage variation over a temperature range and the other bandgap reference circuit is associated with a second amount of reference voltage variation over the temperature range, the first amount of reference voltage variation being less than the second amount of reference voltage variation. ### Claim 12 (depends on 10) The bandgap reference circuit of claim 10 wherein the input bandgap circuit includes a voltage-to-current circuit to receive the input bandgap reference voltage from the other bandgap reference circuit and generate an input bandgap reference current based at least in part on the input bandgap reference voltage. ### Claim 13 (depends on 12) The bandgap reference circuit of claim 12 wherein the input bandgap circuit includes a current digital-to-analog converter to receive the input bandgap reference current from the voltage-to-current circuit, generate the first current based at least in part on the input bandgap reference current, and provide the first current to the node. ### Claim 14 (depends on 13) The bandgap reference circuit of claim 13 wherein the reference voltage circuit includes one or more transistors coupled to the one or more impedance elements, the reference voltage circuit is configured to configure the one or more impedance elements by controlling the one or more transistors based at least in part on the temperature signal. ### Claim 15 (depends on 14) The bandgap reference circuit of claim 14 further comprising a start-up circuit coupled to the error amplifier circuit, the start-up circuit to receive a voltage from a low dropout regulator and power-up the bandgap reference circuit based at least in part on the received voltage, the received voltage being based at least in part on the input bandgap reference voltage from the other bandgap reference circuit. ### Claim 16 (depends on 10) The bandgap reference circuit of claim 10 wherein the second current includes the PTAT current and the first current ### Claim 17 A radio-frequency module comprising: a packaging substrate configured to receive a plurality of components; and a semiconductor die mounted on the packaging substrate, the semiconductor die including a current generation circuit, an input bandgap circuit coupled to a node, and a reference voltage circuit coupled to the node, the current generation circuit configured to generate a Proportional-to-Absolute-Temperature (PTAT) current and provide the PTAT current to the node, the input bandgap circuit configured to receive an input bandgap reference voltage associated with another bandgap reference circuit and control a first current to the node based at least in part on a temperature signal, the first current being associated with the input bandgap reference voltage, the reference voltage circuit including one or more impedance elements, the reference voltage circuit configured to configure the one or more impedance elements based at least in part on the temperature signal, receive a second current via the node, and provide an output bandgap reference voltage based at least in part on the second current passing through the one or more impedance elements. ### Claim 18 (depends on 17) The radio-frequency module of claim 17 further comprising the other bandgap reference circuit configured to provide the input bandgap reference voltage. ### Claim 19 (depends on 18) The radio-frequency module of claim 18 further comprising a low dropout regulator coupled to the other bandgap reference circuit, the low dropout regulator configured to receive the input bandgap reference voltage and provide a regulated voltage based at least in part on the input bandgap reference voltage. ### Claim 20 (depends on 19) The radio-frequency module of claim 19 further comprising a temperature circuit coupled to the low dropout regulator, the temperature sensor circuit configured to receive the regulated voltage and output the temperature signal.