Optical semiconductor relay device for reducing transient voltage between output terminals of the relay and maintaining high operation speed and low capacitance characteristics
View Patent ↗A transient voltage occurring between output terminals during ON/OFF operation is reduced. There are provided a pair of input terminals IN 1 and IN 2, a pair of output terminals OUT 1 and OUT 2, MOSFETs N 1 and N 2 connected between the output terminals, and a drive circuit 10 connected between the input terminals IN 1 and IN 2 and the MOSFETs N 1 and N 2. A light-emitting diode D 1 is connected between the input terminals IN 1 and IN 2. The MOSFETs N 1 and N 2 have their source electrodes electrically connected to each other and their drains connected to the output terminals OUT 1 and OUT 2 respectively. The drive circuit 10 includes a photodiode array FD 1 that supplies a drive voltage to the gates of the MOSFETs N 1 and N 2, and a discharge circuit 11, connected between the gate electrodes and the source electrodes of the MOSFETs N 1 and N 2, that discharges electric charges accumulated on each gate electrode.
1. An optical semiconductor relay device comprising:
a pair of input terminals;
a pair of output terminals;
a plurality of FETs connected between said output terminals; and
a drive circuit that drives said plurality of FETs; wherein
a single control signal is supplied to said pair of input terminals and a single output signal is outputted to said pair of output terminals;
said plurality of FETs are the same type and have their source electrodes electrically connected to each other;
said drive circuit is configured so that gate electrodes of said FETs are not electrically short-circuited to each other;
said FETs are turned on/off by said single control signal; and
said drive circuit includes:
an optical/electrical transducer that supplies a drive voltage to the gates of said plurality of FETs; and
a discharge circuit, connected between the gate electrodes and the source electrodes of said plurality of FETs, that discharges electric charges accumulated on each gate electrode,
wherein:
said optical/electrical transducer is a single continuous photodiode array,
said plurality of FETS include a first FET and a second FET,
a drain electrode of said first FET is connected to one of said output terminals, and
a drain electrode of said second FET is connected to the other of said output terminals.
2. The optical semiconductor relay device as defined in claim 1 , wherein
said optical/electrical transducer is a photodiode array; and
said discharge circuit comprises:
an npn transistor having its collector connected to an anode of said photodiode array, its base connected to a cathode of said photodiode array, and its emitter connected to the source electrodes of said plurality of FETs;
a first pnp transistor having its emitter connected to the gate electrode of one of said plurality of FETs, its base connected to the anode of said photodiode array, and its collector connected to the cathode of said photodiode array;
a second pnp transistor having its emitter connected to the gate electrode of the other of said plurality of FETs, its base connected to the anode of said photodiode array, and its collector connected to the cathode of said photodiode array;
a first diode group having its anode connected to the emitter of said npn transistor and its cathode connected to the base of said npn transistor;
a second diode group having its anode connected to the base of said first pnp transistor and its cathode connected to the emitter of said first pnp transistor; and
a third diode group having its anode connected to the base of said second pnp transistor and its cathode connected to the emitter of said second pnp transistor.
3. The optical semiconductor relay device as defined in claim 2 , wherein at least one of said first, second, and third diode groups comprises by a single diode or a plurality of diodes connected in series.
4. The optical semiconductor relay device as defined in claim 3 further comprising a second resistance element in parallel with said photodiode array.
5. The optical semiconductor relay device as defined in claim 3 further comprising a leakage diode having its cathode connected to the anode of said photodiode array and its anode connected to the cathode of said photodiode array.
6. The optical semiconductor relay device as defined in claim 2 comprising a first resistance element instead of said first diode group.
7. The optical semiconductor relay device as defined in claim 2 further comprising a second resistance element instead of said photodiode array.
8. The optical semiconductor relay device as defined in claim 2 further comprising a leakage diode having its cathode connected to the anode of said photodiode array and its anode connected to the cathode of said photodiode array.
9. The optical semiconductor relay device as defined in claim 1 , wherein the drain electrode of each of the first and second FETs is not connected to a gate electrode, a source electrode and a drain electrode of the other one of the first and second FETs.
10. The optical semiconductor relay device as defined in claim 1 , wherein said discharge circuit comprises a plurality of bipolar transistors.
11. The optical semiconductor relay device as defined in claim 1 , wherein the drain electrode of said first FET is directly connected to said one output terminal, and the drain electrode of said second FET is directly connected to said other output terminal.
12. An optical semiconductor relay device comprising:
a pair of input terminals;
a pair of output terminals;
a plurality of FETs connected between said output terminals; and
a drive circuit that drives said plurality of FETs; wherein
said plurality of FETs are the same type and have their source electrodes electrically connected to each other;
said drive circuit is configured so that gate electrodes of said FETs are not electrically short-circuited to each other; and
said drive circuit includes:
an optical/electrical transducer that supplies a drive voltage to the gates of said plurality of FETs; and
a discharge circuit, connected between the gate electrodes and the source electrodes of said plurality of FETs, that discharges electric charges accumulated on each gate electrode,
wherein said discharge circuit comprises:
an npn transistor having its collector connected to an anode of said photodiode array, its base connected to a cathode of said photodiode array, and its emitter connected to the source electrodes of said plurality of FETs;
a first pnp transistor having its emitter connected to the gate electrode of one of said plurality of FETs, its base connected to the anode of said photodiode array, and its collector connected to the cathode of said photodiode array;
a second pnp transistor having its emitter connected to the gate electrode of the other of said plurality of FETs, its base connected to the anode of said photodiode array, and its collector connected to the cathode of said photodiode array,
wherein said optical/electrical transducer is a single continuous photodiode array.