Cascoded rectifier

Abstract

A high voltage rectifier device exhibiting low forward resistance and fast switching time formed of a high voltage structure connected in a cascode configuration with a low voltage structure. The high voltage structure is a bidirectional normally on semiconductor switch have two pairs of gate and source terminals which shuts off if either of the gate terminals is reverse biased. The low voltage structure is a diode, preferably a Schottky or barrier diode. The device is advantageously formed as an integrated circuit. With one of the terminal pairs of the switch clamped to zero volts, the device behaves as a diode, or the second terminal pair can be employed to provide the functions of a three terminal controlled rectifier. Among other possible applications are integrated circuits using four of the devices as a bridge rectifier, and as an anti-parallel diode for connection with an IGBT.

1. A switched high voltage rectifier device including:
 a low voltage structure comprised of a diode;  
 a high voltage structure comprised of a bidirectional normally on semiconductor switch, wherein the high and low voltage structures are connected in a cascode conflauration wherein:  
 a cathode terminal of the diode is connected to a first source terminal of the bidirectional switch;  
 an anode terminal of the diode is connected to a first gate terminal of the bidirectional switch, and to a signal input terminal; and  
 a second source terminal of the bidirectional switch is connected to a signal output terminal, and  
 a coupling structure is provided between the second source terminal and a second gate terminal of the bidirectional switch.  
 
     
     
       2. A device according to  claim 1 , wherein the low and high voltage structures are fabricated on a common substrate and encapsulated to form an integrated circuit. 
     
     
       3. A device comprising four rectifier devices according to  claim 1 , constructed and configured to function as a full bridge rectifier. 
     
     
       4. A device according to  claim 1 , wherein the coupling structure is an externally controlled voltage source, whereby the device functions as a three terminal controlled rectifier. 
     
     
       5. A device according to  claim 1 , wherein the low voltage structure is a Schottky or a barrier diode. 
     
     
       6. A device according to  claim 1 , wherein the device is constructed and configured to function as a diode. 
     
     
       7. A device according to  claim 1 , wherein the device is constructed and configured to function as a three terminal controlled rectifier. 
     
     
       8. A device according to  claim 1 , wherein the coupling structure is a direct connection, whereby the device functions as a diode. 
     
     
       9. A bridge rectifier device comprising first, second, third, and fourth switched rectifier devices as described in  claim 8 , wherein:
 the input terminal of the first switched rectifier and the output terminal of the fourth switched rectifier are connected to a first bridge input terminal;  
 the input terminal of the second switched rectifier and the output terminal of the third switched rectifier are connected to a second bridge input terminal;  
 the output terminal of the first and second switched rectifiers are connected to a first bridge output terminal;  
 the input terminals of the third and fourth switched rectifiers are connected to a second bridge output terminal; and  
 the bridge rectifier device is adapted to receive an AC input voltage at the bridge input terminals, and to provide a full wave rectified DC voltage at the bridge output terminals.  
 
     
     
       10. A bridge rectifier device according to  claim 9 , wherein the four rectifier devices are formed on a common substrate as part of a single integrated circuit. 
     
     
       11. A device according to  claim 9 , wherein the coupling structure is a direct connection, whereby the device functions as a diode. 
     
     
       12. A device according to  claim 8 , in combination with an IGBT, the IGBT having emiffer and collector terminals thereof connected to the anode and cathode terminals of the rectifier device in an antiparallel relationship. 
     
     
       13. A combined device according to  claim 12 , wherein the rectifier device and the IGBT are formed on a common substrate as part of a single integrated circuit. 
     
     
       14. A bridge rectifier device comprising first, second, third, and fourth switched rectifier devices as described in  claim 1 , wherein:
 an anode terminal of the first switched rectifier and a cathode terminal of the fourth switched rectifier are connected to a first bridge input terminal;  
 an anode terminal of the second switched rectifier and a cathode terminal of the third switched rectifier are connected to a second bridge input terminal;  
 cathode terminals of the first and second switched rectifiers are connected to a first bridge output terminal;  
 anode terminals of the third and fourth switched rectifiers are connected to a second bridge output terminal; and  
 the bridge rectifier device is adapted to receive an AC input voltage at the bridge input terminals, and to provide a full wave rectified DC voltage at the bridge output terminals.  
 
     
     
       15. A bridge rectifier device according to  claim 14 , wherein the four rectifier devices are formed on a common substrate as part of a single integrated circuit. 
     
     
       16. A circuit comprising a switched high voltage rectifier device including:
 a low voltane  voltage structure comprised of a diode;  
 a high voltage structure comprised of a bidirectional normally on semiconductor switch,  
 wherein the high and low voltage structures are connected in a cascode configuration:  
 further comprising an IGBT, the IGBT having emitter and collector terminals thereof connected to anode and cathode terminals of the rectifier device in an antiparallel relationship.  
 
     
     
       17. A circuit according to  claim 16 , wherein the rectifier device and the IGBT are formed on a common substrate as part of a single integrated circuit. 
     
     
       18. A switched high voltage rectifier device comprising:
   a low voltage structure comprised of a diode;        a high voltage structure comprised of a normally on semiconductor switch,        wherein the high and low voltage structures are connected in a cascode configuration, further wherein        a cathode terminal of the diode is connected to a first source terminal of the switch;        an anode terminal of the diode is connected to a gate terminal of the switch, and to a signal input terminal; and        a second source terminal of the switch is connected to a signal output terminal.     
     
     
       19. A device according to  claim 18 , wherein:
   the switch is bidirectional and the gate terminal comprises a first gate terminal and there is further provided a second gate terminal;        the anode terminal of the diode is connected to the first gate terminal; and        a coupling structure is provided between the second source terminal and the second gate terminal of the bidirectional switch.