This invention discloses rectifying circuits using normally "off" Junction Effect Transistor. By connecting the gate of the JFET to the higher bias terminal of the output coil of the transformer, the forward biased turn on function of the normally "off" JFETs can be achieved. Therefore, the normally "off" JFET can be used as synchronized zero voltage switching rectifier with very low voltage drop. Since normally "off" JFET is a majority carrier device, very high frequency response can be achieved. This kind of circuitry can replace the P-N junction and/or Schottky rectifiers especially when the supply voltage drops below three volts.
This is a continuation of copending application Ser. No. 09/453,136 filed on Dec. 2, 1999 which is hereby incorporated by reference to this specification which designated the U.S.
This application is a continuation of Ser. No. 09/453,136 filed Dec. 2, 1999, which claims a priority date of Dec. 7, 1998, benefited from a previously filed Provisional Application No. 60/111,197 filed on Dec. 7, 1998 by a same Inventor of this Patent Application.
A voltage converter uses a component such as a JFET or four-terminal power MOSFET having no body diode and exhibiting no body diode conduction characteristic as a synchronous rectifier to reduce switching losses and body diode conduction losses and to support high frequency switching so that use of smaller components and higher current densities can be achieved. These effects are enhanced by a self-driven circuit utilizing positive feedback to enhance switching speed and reduce switching losses which increase with switching frequency.
A bi-directional converter for converting voltage bi-directionally between a high voltage bus and a low voltage bus, having a switching converter connected across the high voltage bus, the switching converter having first and second switching modules connected in series across the high voltage bus, a switched node disposed between the switching modules being coupled to an inductor, the first and second switching modules being controllable so that the switching converter can be operated as a buck converter or a boost converter depending upon the direction of conversion from the high voltage bus to the low voltage bus or vice versa; the mid-voltage bus being coupled to a first full bridge switching circuit having two pairs of series connected switches with switched nodes between each of the pairs of switches being connected across a first winding of a transformer having a preset turns ratio.
