# US 10,483,966 B2 · Switching circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,483,966 B2 - Document ID: US10483966B2 - Status: Granted - Kind: B2 - Application number: 16/226,081 - Filed: 2018-12-19 - Published: 2019-05-16 - Granted: 2019-11-19 - Earliest claimed: 2016-08-31 - Assignees: Panasonic Intellectual Property Management Co., Ltd. - Applicants: Panasonic Intellectual Property Management Co., Ltd. - Inventors: Takahiro Uehara; Takuya Ishii; Hiroyuki Handa; Atsushi Kitagawa; Takeshi Tanaka - Web page: https://patentgrep.com/patent/US10483966B2 ## CPC - H03K 17/64: having inductive loads - H03K 17/122: {in field-effect transistor switches} - H03K 17/127: {in composite switches} - H02M 1/0009: {Devices or circuits for detecting current in a converter} - H03K 2217/0081: Power supply means, e.g. to the switch driver - 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 switching circuit includes: a drive power supply; a first transistor and a second transistor; a drive signal source; and a drive circuit. Each of the first transistor and the second transistor includes: a drain electrode and a source electrode in which a main current flows when a corresponding one of the first transistor and the second transistor is ON; a first source terminal for passing the main current; and a second source terminal. Here, the first source terminal is connected to the source electrode at an impedance lower than an impedance of the second source terminal. ## Claims ### Claim 1 A switching circuit, comprising: a drive power supply which includes a positive electrode terminal and a negative electrode terminal, and outputs a predetermined drive voltage; a first transistor and a second transistor which are connected in parallel; a drive signal source which outputs a drive pulse signal for turning on and off the first transistor and the second transistor; and a drive circuit, which includes a power supply terminal and a ground terminal, receives supply of electric power from the drive power supply, and outputs, according to the drive pulse signal, a first drive signal for turning on and off the first transistor and a second drive signal for turning on and off the second transistor, wherein each of the first transistor and the second transistor includes: a drain electrode and a source electrode in which a main current flows when a corresponding one of the first transistor and the second transistor is ON; a gate electrode which changes an impedance between the drain electrode and the source electrode according to a corresponding one of the first drive signal and the second drive signal; a gate terminal connected to the gate electrode; a drain terminal connected to the drain electrode; a first source terminal connected to the source electrode for passing the main current between the drain electrode and the source electrode; and a second source terminal connected to the source electrode for detecting a source voltage and flowing a gate drive current, the second source terminal being provided in addition to the first source terminal, the first source terminal is connected to the source electrode at an impedance lower than an impedance of the second source terminal, the drain terminal of the first transistor and the drain terminal of the second transistor are connected to each other, the first source terminal of the first transistor and the first source terminal of the second transistor are connected to each other, the gate terminal of the first transistor receives the first drive signal, the gate terminal of the second transistor receives the second drive signal, and the second source terminal of the first transistor and the second source terminal of the second transistor are individually and separately connected to a portion of a wiring line which connects the negative electrode terminal of the drive power supply and the ground terminal of the drive circuit. ### Claim 2 (depends on 1) The switching circuit according to claim 1, wherein the first transistor and the second transistor have substantially equal rated currents, and the first drive signal and the second drive signal which are supplied by the drive circuit are set to be substantially the same. ### Claim 3 (depends on 2) The switching circuit according to claim 2, further comprising: a bypass capacitor which becomes an alternating current source for the first transistor and the second transistor, wherein the bypass capacitor, the first transistor, and the second transistor are connected for passing the main current from a load to a negative electrode terminal of the bypass capacitor through the first transistor and the second transistor, and the first transistor, the second transistor, and the bypass capacitor are arranged on a wiring board such that an impedance between the first source terminal of the first transistor and the negative electrode terminal of the bypass capacitor and an impedance between the first source terminal of the second transistor and the negative electrode terminal of the bypass capacitor are substantially equal to each other. ### Claim 4 (depends on 3) The switching circuit according to claim 3, wherein the first transistor, the second transistor, and the bypass capacitor are arranged on the wiring board such that a perpendicular bisector of a line segment to connect the source terminal of the first transistor and the source terminal of the second transistor passes through the negative electrode terminal of the bypass capacitor in a plan view of the wiring board. ### Claim 5 (depends on 4) The switching circuit according to claim 4, further comprising: a third transistor and a fourth transistor, wherein each of the third transistor and the fourth transistor includes a drain terminal and a source terminal in which a main current flows, on the wiring board, the drain terminal of the third transistor, the drain terminal of the fourth transistor, and a positive electrode terminal of the bypass capacitor are connected to one another, the drain terminal of the first transistor, the drain terminal of the second transistor, the source terminal of the third transistor, and the source terminal of the fourth transistor are connected to one another, and the third transistor, the fourth transistor, and the bypass capacitor are arranged on the wiring board such that a perpendicular bisector of a line segment to connect the drain terminal of the third transistor and the drain terminal of the fourth transistor passes through the positive electrode terminal of the bypass capacitor in a plan view of the wiring board. ### Claim 6 (depends on 3) The switching circuit according to claim 3, further comprising: the wiring board; a first connector connected to the source terminal of the first transistor in a proximity of the first transistor arranged on the wiring board; a second connector connected to the source terminal of the second transistor in a proximity of the second transistor arranged on the wiring board; and a sub wiring board which is connected to the wiring board by the first connector and the second connector on the first transistor and the second transistor, and on which the bypass capacitor is arranged, wherein the first connector, the second connector, and the bypass capacitor are arranged on the wiring board such that a perpendicular bisector of a line segment to connect the first connector and the second connector passes through the negative electrode terminal of the bypass capacitor in a plan view of the wiring board. ### Claim 7 (depends on 6) The switching circuit according to claim 6, further comprising: a third transistor and a fourth transistor, wherein each of the third transistor and the fourth transistor includes a drain terminal and a source terminal in which a main current flows, the switching circuit further comprising: a third connector connected to the drain terminal of the third transistor in a proximity of the third transistor arranged on the wiring board; and a fourth connector connected to the drain terminal of the fourth transistor in a proximity of the fourth transistor arranged on the wiring board, wherein the third connector and the fourth connector are connected to the sub wiring board, and the third connector, the fourth connector, and the bypass capacitor are arranged on the sub wiring board such that a perpendicular bisector of a line segment to connect the third connector and the fourth connector passes through the positive electrode terminal of the bypass capacitor in a plan view of the sub wiring board. ### Claim 8 (depends on 6) The switching circuit according to claim 6, wherein the sub wiring board also functions as a heat sink for the first transistor and the second transistor.