# US 9,438,231 B2 · Gate drive circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,438,231 B2 - Document ID: US9438231B2 - Status: Granted - Kind: B2 - Application number: 14/690,429 - Filed: 2015-04-19 - Published: 2015-08-06 - Granted: 2016-09-06 - Earliest claimed: 2013-08-23 - Assignees: Panasonic Intellectual Property Management Co., Ltd. - Applicants: Panasonic Intellectual Property Management Co., Ltd. - Inventors: Shuichi Nagai - Web page: https://patentgrep.com/patent/US9438231B2 ## CPC - H03K 17/691: using transformer coupling - H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters - H03K 17/16: Modifications for eliminating interference voltages or currents - H03K 17/18: Modifications for indicating state of switch - H03K 17/6877: {the control circuit comprising active elements different from those used in the output circuit} - H03K 17/693: Switching arrangements with several input- or output-terminals, e.g. multiplexers, distributors (logic circuits H03K19/00; code converters H03M5/00, H03M7/00) - H03K 2217/009: Resonant driver circuits - 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) - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) ## Abstract A gate drive circuit in an aspect of the present disclosure includes: a first electromagnetic resonant coupler that isolatedly transmits a transmission signal from the primary side to the secondary side, and also isolatedly transmits a reflected signal from the secondary side to the primary side; a modulator circuit that modulates a radio-frequency wave with an input signal to generate the transmission signal; a demodulator circuit that demodulates the transmission signal to generate an output signal; a variable capacitance diode into which the transmission signal is input from the first electromagnetic resonant coupler, the variable capacitance diode disposed on the secondary side, the variable capacitance diode allowing a capacitance thereof to vary according to a monitor signal; and a reflected signal rectifier circuit that rectifies the reflected signal input to generate a monitor output signal. ## Claims ### Claim 1 A gate drive circuit comprising: a first electromagnetic resonant coupler that isolatedly transmits a transmission signal from a primary side of the gate drive circuit to a secondary side of the gate drive circuit, and isolatedly transmits a reflected signal from the secondary side to the primary side, the primary side and the secondary side isolated from each other, the reflected signal generated by reflecting the transmission signal on the secondary side; a modulator circuit that modulates a radio-frequency wave with an input signal to generate the transmission signal and outputs the transmission signal to the first electromagnetic resonant coupler, the modulator circuit disposed on the primary side; a demodulator circuit that demodulates the transmission signal input from the first electromagnetic resonant coupler to generate an output signal and outputs the output signal to a semiconductor switch, the demodulator circuit disposed on the secondary side; a variable capacitance diode into which the transmission signal is input from the first electromagnetic resonant coupler, the variable capacitance diode disposed on the secondary side, the variable capacitance diode allowing a capacitance thereof to vary according to a monitor signal; and a reflected signal rectifier circuit that rectifies the reflected signal input from the first electromagnetic resonant coupler to generate a monitor output signal, the reflected signal rectifier circuit disposed on the primary side. ### Claim 2 (depends on 1) The gate drive circuit according to claim 1, wherein the demodulation circuit includes a rectifier circuit that rectifies the transmission signal to generate the output signal. ### Claim 3 (depends on 2) The gate drive circuit according to claim 2, wherein: the variable capacitance diode is disposed between the first electromagnetic resonant coupler and the rectifier circuit; and the reflected signal is generated by reflecting the transmission signal between the first electromagnetic resonant coupler and the rectifier circuit. ### Claim 4 (depends on 2) The gate drive circuit according to claim 2, further comprising: a transmission line extending between the first electromagnetic resonant coupler and the rectifier circuit; an output terminal through which the output signal is output to a semiconductor switch, the output terminal disposed on the secondary side; an output reference terminal through which an output reference potential is applied to the semiconductor switch, the output reference terminal disposed on the secondary side, wherein one end of the variable capacitance diode is connected to the transmission line, and the other end of the variable capacitance diode is connected to the output reference terminal. ### Claim 5 (depends on 1) The gate drive circuit according to claim 1, further comprising a signal separator that separates the transmission signal and reflected signal from each other, the signal separator disposed between the modulator circuit and the first electromagnetic resonant coupler on the primary side. ### Claim 6 (depends on 1) The gate drive circuit according to claim 1, further comprising a directional coupler that allows the transmission signal to pass from the modulator circuit to the first electromagnetic resonant coupler and also allows the reflected signal to pass from the first electromagnetic resonant coupler to the reflected signal rectifier circuit, the directional coupler disposed between the modulator circuit and the first electromagnetic resonant coupler on the primary side. ### Claim 7 (depends on 1) The gate drive circuit according to claim 1, wherein the first electromagnetic resonant coupler includes: a first terminal into which the transmission signal is input, the first terminal disposed on the primary side; a second terminal from which the transmission signal input from the first terminal is output and into which the reflected signal is input, the second terminal disposed on the secondary side; and a third terminal from which the reflected signal input from the second terminal is output, the third terminal disposed on the primary side, and the reflected signal rectifier circuit rectifies the reflected signal output from the third terminal. ### Claim 8 (depends on 1) The gate drive circuit according to claim 1, wherein the variable capacitance diode allows an amplitude of the reflected signal to vary according to the capacitance thereof. ### Claim 9 (depends on 1) The gate drive circuit according to claim 1, further comprising a radio-frequency oscillator that generates the radio-frequency wave and outputs the radio-frequency wave to the modulator circuit, the radio-frequency oscillator disposed on the primary side. ### Claim 10 (depends on 1) The gate drive circuit according to claim 1, wherein the modulator circuit includes any one of a mixer circuit that mixes the radio-frequency wave and the input signal and a switch circuit that selectively outputs the radio-frequency wave according to the input signal. ### Claim 11 (depends on 1) The gate drive circuit according to claim 1, further comprising: an input terminal through which the input signal is input to the modulator circuit, the input terminal disposed on the primary side; an output terminal through which the output signal is output to a semiconductor switch, the output terminal disposed on the secondary side; and a monitor terminal through which the monitor signal is input to the reflected signal rectifier circuit, the monitor terminal disposed on the secondary side. ### Claim 12 A gate drive circuit comprising: a first electromagnetic resonant coupler that isolatedly transmits a first radio-frequency wave from a primary side of the gate drive circuit to a secondary side of the gate drive circuit, and isolatedly transmits a reflected signal from the secondary side to the primary side, the primary side and the secondary side isolated from each other, the reflected signal generated by reflecting the first radio-frequency wave on the secondary side; a modulator circuit that modulates a second radio-frequency wave with an input signal to generate the transmission signal and outputs the transmission signal to the second electromagnetic resonant coupler, the modulator circuit disposed on the primary side; a second electromagnetic resonant coupler that isolatedly transmits a transmission signal from the primary side to the secondary side; a demodulator circuit that demodulates the transmission signal input from the second electromagnetic resonant coupler to generate an output signal, the demodulator circuit disposed on the secondary side; a variable capacitance diode into which the first radio-frequency wave is input from the first electromagnetic resonant coupler, the variable capacitance diode disposed on the secondary side, the variable capacitance diode allowing a capacitance thereof to vary according to a monitor signal; and a reflected signal rectifier circuit that rectifies the reflected signal input from the first electromagnetic resonant coupler to generate a monitor output signal, the reflected signal rectifier circuit disposed on the primary side. ### Claim 13 (depends on 12) The gate drive circuit according to claim 12, wherein the demodulation circuit includes a rectifier circuit that rectifies the transmission signal to generate the output signal. ### Claim 14 (depends on 12) The gate drive circuit according to claim 12, further comprising a transmission line extending from the first electromagnetic resonant coupler to the secondary side, wherein: one end of the variable capacitance diode is connected to the transmission line; and the reflected signal is generated by reflecting the first radio-frequency wave on the transmission line. ### Claim 15 (depends on 12) The gate drive circuit according to claim 12, further comprising: a transmission line extending from the first electromagnetic resonant coupler to the secondary side; and a reference potential line that applies a reference potential, the reference potential line disposed on the secondary side, wherein one end of the variable capacitance diode is connected to the transmission line, and the other end of the variable capacitance diode is connected to the reference potential line. ### Claim 16 (depends on 12) The gate drive circuit according to claim 12, wherein the variable capacitance diode causes an amplitude of the reflected signal to vary, when the capacitance of the variable capacitance diode varies. ### Claim 17 (depends on 12) The gate drive circuit according to claim 12, further comprising a radio-frequency oscillator that generates the first and second radio-frequency waves, the radio-frequency oscillator disposed on the primary side. ### Claim 18 (depends on 17) The gate drive circuit according to claim 17, wherein the radio-frequency oscillator allows an oscillation frequency thereof to vary according to the monitor output signal. ### Claim 19 (depends on 12) The gate drive circuit according to claim 12, wherein the modulator circuit allows an amplitude of the second radio-frequency wave to vary according to the monitor output signal. ### Claim 20 (depends on 12) The gate drive circuit according to claim 12, wherein the modulator circuit includes any one of a mixer circuit that mixes the second radio-frequency wave and the input signal and a switch circuit that selectively outputs the second radio-frequency wave according to the input signal.