# US 10,771,027 B2 · Operational amplifier circuit and current detection device using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,771,027 B2 - Document ID: US10771027B2 - Status: Granted - Kind: B2 - Application number: 16/253,479 - Filed: 2019-01-22 - Published: 2019-09-26 - Granted: 2020-09-08 - Earliest claimed: 2018-03-23 - Assignees: Fuji Electric Co., Ltd. - Applicants: Fuji Electric Co., Ltd. - Inventors: Motomitsu Iwamoto - Web page: https://patentgrep.com/patent/US10771027B2 ## CPC - H03F 3/45179: {using MOSFET transistors as the active amplifying circuit (H03F3/45278 takes precedence)} - G01R 19/0092: {Measuring current only} - G01R 31/2639: {for testing field-effect devices, e.g. of MOS-capacitors (G01R31/2621 takes precedence)} - G05F 1/56: using semiconductor devices in series with the load as final control devices (G05F1/461 takes precedence) - G05F 3/26: Current mirrors - H03F 3/45183: {Long tailed pairs (H03F3/4521, H03F3/45237 take precedence)} - H03K 17/0822: {in field-effect transistor switches} - H03F 2203/45586: the IC comprising offset generating means - H03K 2217/0027: Measuring means of, e.g. currents through or voltages across the switch - H03F: AMPLIFIERS - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract An operational amplifier circuit includes a potential control circuit connected between a current sense semiconductor element connected in parallel with a main semiconductor element and a current detection resistor. The potential control circuit controls an output potential of the current sense semiconductor element to be equal to that of the main semiconductor element. The potential control circuit includes a current control element controlling an output current of the current sense semiconductor element and an operational amplifier outputting a signal corresponding to an output potential difference between the current sense semiconductor element and the main semiconductor element to the current control element. An input offset voltage polarity determination unit determines a polarity of an input offset voltage of the operational amplifier according to the output potential difference. The polarity of the input offset voltage is controlled to be constant based on polarity determination of the input offset voltage. ## Claims ### Claim 1 An operational amplifier circuit comprising: a potential control circuit connected between a current detection resistor and a current sense semiconductor element connected in parallel with a main semiconductor element which is connected to a power source and configured to supply a drive current to a load, the potential control circuit being configured to control an output potential of the current sense semiconductor element to be equal to an output potential of the main semiconductor element, the potential control circuit including a current control element connected between the current sense semiconductor element and the current detection resistor, and an operational amplifier, the output potential of the current sense semiconductor element being input to one of a non-inverting input terminal or an inverting input terminal of the operational amplifier, the output potential of the main semiconductor element being input to another one of the non-inverting input terminal or the inverting input terminal, and the operational amplifier configured to output a control signal corresponding to a potential difference between the current sense semiconductor element and the main semiconductor element to the current control element; and an input offset voltage polarity determination circuit configured to determine a polarity of an input offset voltage of the operational amplifier according to the potential difference between the current sense semiconductor element and the main semiconductor element, wherein the operational amplifier controls the polarity of the input offset voltage to be constant on a basis of a polarity determination signal of the input offset voltage polarity determination circuit. ### Claim 2 (depends on 1) The operational amplifier circuit according to claim 1, wherein the input offset voltage polarity determination circuit includes a chopper inverter comparator in which the output potential of the current sense semiconductor element and the output potential of the main semiconductor element are input. ### Claim 3 (depends on 1) The operational amplifier circuit according to claim 1, wherein the operational amplifier includes: a differential amplifier circuit in which a pair of semiconductor elements forming a current mirror circuit and a pair of differential pair elements forming a differential pair are connected in series to each other; a push-pull output stage circuit in which a differential output of the differential amplifier circuit is input; a first selector section configured to select one of the non-inverting input terminal or the inverting input terminal to be connected to a control terminal of one of the pair of differential pair elements and select another one of the non-inverting input terminal or the inverting input terminal to be connected to a control terminal of another one of the pair of differential pair elements; a second selector section configured to select one of the pair of semiconductor elements of the current mirror circuit to be diode-connected; and a third selector section configured to select an output side of the differential amplifier circuit to be connected to the push-pull output stage circuit, wherein the input offset voltage polarity determination circuit is configured to supply the polarity determination signal as a selection signal to the first selector section, the second selector section, and the third selector section. ### Claim 4 (depends on 1) The operational amplifier circuit according to claim 1, wherein a toggle flip-flop is connected between the input offset voltage determination circuit and the operational amplifier. ### Claim 5 (depends on 1) A current detection device comprising the operational amplifier circuit according to claim 1. ### Claim 6 (depends on 2) The operational amplifier circuit according to claim 2, wherein the operational amplifier includes: a differential amplifier circuit in which a pair of semiconductor elements forming a current mirror circuit and a pair of differential pair elements forming a differential pair are connected in series to each other; a push-pull output stage circuit in which a differential output of the differential amplifier circuit is input; a first selector section configured to select one of the non-inverting input terminal or the inverting input terminal to be connected to a control terminal of one of the pair of differential pair elements and select another one of the non-inverting input terminal or the inverting input terminal to be connected to a control terminal of another one of the pair of differential pair elements; a second selector section configured to select one of the pair of semiconductor elements of the current mirror circuit to be diode-connected; and a third selector section configured to select an output side of the differential amplifier circuit to be connected to the push-pull output stage circuit, wherein the input offset voltage polarity determination circuit is configured to supply the polarity determination signal as a selection signal to the first selector section, the second selector section, and the third selector section. ### Claim 7 (depends on 2) The operational amplifier circuit according to claim 2, wherein a toggle flip-flop is connected between the input offset voltage determination circuit and the operational amplifier. ### Claim 8 (depends on 3) The operational amplifier circuit according to claim 3, wherein a toggle flip-flop is connected between the input offset voltage determination circuit and the operational amplifier. ### Claim 9 (depends on 6) The operational amplifier circuit according to claim 6, wherein a toggle flip-flop is connected between the input offset voltage determination circuit and the operational amplifier. ### Claim 10 (depends on 2) A current detection device comprising the operational amplifier circuit according to claim 2. ### Claim 11 (depends on 3) A current detection device comprising the operational amplifier circuit according to claim 3. ### Claim 12 (depends on 4) A current detection device comprising the operational amplifier circuit according to claim 4. ### Claim 13 (depends on 6) A current detection device comprising the operational amplifier circuit according to claim 6. ### Claim 14 (depends on 7) A current detection device comprising the operational amplifier circuit according to claim 7. ### Claim 15 (depends on 8) A current detection device comprising the operational amplifier circuit according to claim 8. ### Claim 16 (depends on 9) A current detection device comprising the operational amplifier circuit according to claim 9.