Rectifying element and voltage converter comprising such a rectifying element

Abstract

A rectifying element includes a MOS transistor series-connected with a Schottky diode. A bias voltage is applied between the control terminal of the MOS transistor and the terminal of the Schottky diode opposite to the transistor. A pair of the rectifying elements are substituted for diodes of a rectifying bridge circuit. Alternatively, the control terminal bias is supplied from a cross-coupling against the Schottky diodes. In another implementation, the Schottky diodes are omitted and the bias voltage applied to control terminals of the MOS transistors is switched in response to cross-coupled divided source-drain voltages of the MOS transistors. The circuits form components of a power converter.

1 . A rectifying element, comprising:
 a MOS transistor directly electrically connected in series with a Schottky diode between a first terminal and a second terminal;   a voltage generator configured to apply a substantially constant voltage between a control terminal of the MOS transistor and the second terminal, the substantially constant voltage having a value such that the MOS transistor is conducting when the Schottky diode is conducting.   
     
     
         2 . The rectifying element of  claim 1 , wherein a source of the MOS transistor is directly electrically connected to a cathode of the Schottky diode. 
     
     
         3 . The rectifying element of  claim 1 , wherein the first terminal is a drain of the MOS transistor and the second terminal is an anode of the Schottky diode. 
     
     
         4 . The rectifying circuit of  claim 1 , wherein the MOS transistor is of N-channel enrichment type. 
     
     
         5 . A voltage converter, comprising:
 a rectifying bridge circuit comprising:
 a first diode; 
 a first rectifying element coupled in series with the first diode between a first terminal and a second terminal; 
 a second diode; 
 a second rectifying element coupled in series with the second diode between the first terminal and the second terminal; 
   wherein each of the first and second rectifying elements comprises a MOS transistor series-connected with a Schottky diode between the second terminal and an intermediate terminal; and   a voltage generator configured to apply a substantially constant voltage between a control terminal of the MOS transistor and the second terminal, the constant voltage having a value such that the MOS transistor is conducting when the Schottky diode is conducting.   
     
     
         6 . The converter of  claim 5 , wherein the intermediate terminal is an input of the converter and the first and second terminals are an output of the converter. 
     
     
         7 . The converter of  claim 5 , further comprising:
 an inductor coupled between the intermediate terminal and a series node; and   a transistor switch driven by a pulse width modulation control signal and coupled between the second terminal and the series node.   
     
     
         8 . The converter of  claim 5 , further comprising:
 a first inductive element coupled in series between the first rectifying element and the first diode; and   a first transistor switch driven by a pulse width modulation control signal and coupled between a first junction point and the second terminal, wherein the first junction point connects the first inductive element and the first diode.   
     
     
         9 . The converter of  claim 8 , further comprising:
 a second inductive element coupled in series with the second rectifying element and the second diode, the second inductive element located between the second rectifying element and the second diode; and   a second transistor switch driven by a pulse width modulation control signal and coupled between a second junction point and the second terminal, wherein the second junction point connects the second inductive element and the second diode.   
     
     
         10 . The converter of  claim 5 , wherein a source of the MOS transistor is directly electrically connected to a cathode of the Schottky diode. 
     
     
         11 . The converter of  claim 5 , wherein the intermediate terminal is a drain of the MOS transistor and the second terminal is an anode of the Schottky diode. 
     
     
         12 . The converter of  claim 5 , wherein the MOS transistor is of N-channel enrichment type. 
     
     
         13 . The converter of  claim 5 , wherein the first rectifying element is directly electrically connected to the first diode at a first intermediate terminal, and wherein the second rectifying element is directly electrically connected to the second diode at a second intermediate terminal. 
     
     
         14 . The converter of  claim 13 , wherein the first and second intermediate terminals are an input of the converter and the first and second terminals are an output of the converter. 
     
     
         15 . The converter of  claim 14 , further comprising:
 an inductor coupled between the first terminal and a third intermediate terminal;   a transistor switch coupled between the third intermediate terminal and the second terminal; and   a diode coupled between the third intermediate terminal and an output.