Fast turn on switch circuit with parallel MOS controlled thyristor and silicon controlled rectifier
AssigneeHarris Corporation
InventorVictor A. K. Temple
Life of this patent
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Abstract
A fast turn-on electrical switch circuit includes a silicon controlled rectifier ("SCR") connected substantially in parallel with a MOS controlled thyristor ("MCT"). When the switch is turned on, the MCT turns on almost immediately and carries the circuit load during the spreading time of the SCR. The SCR subsequently carries the circuit load when it is turned fully on because it has a smaller forward drop, due in part to its larger area and/or higher carrier lifetime. The MCT and SCR may be gated simultaneously from the same or separate sources or the SCR may be gated with a portion of the current from the MCT. The switch may be integrated into a single semiconductor device with alternating MCT regions and SCR regions.
Claims28
A method of turning on a silicon controlled rectifier switch in which the initial forward voltage drop is reduced comprising the steps of:
- connecting a MOS controlled thyristor in a first switched path substantially in parallel with the silicon controlled rectifier in a second switched path;
- and
- turning on the MOS controlled thyristor no later than turning on the silicon controlled rectifier so that the MOS controlled thyristor reduces the initial forward voltage drop in the circuit.
An electrical switch circuit comprising a MOS controlled thyristor in a first switched path that is connected substantially in parallel with a second switched path comprising a silicon controlled rectifier.
A semiconductor switch comprising:
- a silicon controlled rectifier with an initial forward voltage drop responsive to the rate of change of a current there across;
- a MOS controlled thyristor in a first switched path that is substantially in parallel with a second switched path comprising said silicon controlled rectifier, said MOS controlled thyristor having a smaller initial forward voltage drop than said silicon controlled rectifier;
- and
- means for turning on said MOS controlled thyristor no later than said silicon controlled rectifier.
An electrical switch comprising:
- first and second switching devices, said first switching device comprising a MOS controlled thyristor and having a faster turn-on time and a higher di/dt capability than said second device;
- and
- switch control means controlling the operation of said first and second switching devices such that at the turn-on of the switch a current initially travels substantially through said first switching device, and subsequently substantially through said second switching device,
- said first switching device having a lower base and lower emitter generally coplanar with the same semiconductor type material as a corresponding lower base and a corresponding lower emitter of said second switching device.
An electrical switch circuit comprising:
- a MOS controlled thyristor having source, drain and gate electrodes;
- a silicon controlled rectifier having source, drain and gate electrodes, said rectifier being electrically connected to said thyristor substantially in parallel so that the sources of the rectifier and the thyristor are common and the drains of the rectifier and the thyristor are common;
- a first gate means for selectively applying an electrical signal to the gate electrode of the thyristor;
- and
- a second gate means for selectively applying a second electrical signal to the gate electrode of the rectifier,
- whereby upon turning on the switch circuit and application of a voltage potential between the source and drain electrodes, the first and second gate control circuits are operated to establish initially substantially all of the current in the circuit through the thyristor and subsequently substantially through the rectifier.
A semiconductor switch comprising:
- a silicon controlled rectifier having a first gate terminal;
- a MOS controlled thyristor having a second gate terminal;
- and
- first control means to operate the first and second gate terminals such that when the switch is operated most of the current through the switch flows initially through the MOS controlled thyristor and subsequently through the silicon controlled rectifier.
An integral semiconductor switch comprising:
- a semiconductor member;
- plural silicon controlled rectifier (SCR) regions in said semiconductor member, each of said SCR regions having an initial forward voltage drop responsive to the rate of change of the current thereacross;
- and
- plural MOS controlled thyristor (MCT) regions in said semiconductor member, each operable one of said MCT regions being connected substantially in parallel with said SCR regions and having a smaller initial forward voltage drop than said SCR regions,
- said MCT regions and said SCR regions being arrayed in alternating portions of said semiconductor member.
A semiconductor device comprising:
- a silicon controlled rectifier having an anode, a cathode and a gate, with its current conduction path between the anode and cathode formed to extend through at least a portion of a semiconductor substrate, and
- a MOS controlled thyristor having an anode, a cathode and a gate, with its current conduction path between the anode and the cathode formed to extend through at least a portion of the substrate, for conduction in the same direction as the current path of said rectifier, substantially in parallel to the current conduction path of said rectifier, and extending into at least a portion of the rectifier current path.
Dependencies are inferred from the claim text.