# US 5,708,573 A · Varactor controlled fixed frequency VHF DC-DC converter

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- Number: US 5,708,573 A
- Document ID: US5708573A
- Status: Granted
- Kind: A
- Application number: 08/593,164
- Filed: 1996-02-01
- Granted: 1998-01-13
- Earliest claimed: 1996-02-01
- Assignees: Hughes Electronics Corporation
- Inventors: David M. Lusher; Wilbur E. Hong; William B. Hwang
- Web page: https://patentgrep.com/patent/US5708573A

## CPC

- H02M 3/155: using semiconductor devices only
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)

## Abstract

A DC to DC converter including a resonant switching circuit (13, 51 , 115, 151, 125, 153); an impedance matching circuit (53) responsive to the resonant switching circuit; a rectifier circuit (55) responsive to the impedance matching circuit; an output filter circuit (57) responsive to rectifier circuit for providing a filtered DC to DC converter voltage output; and a varactor diode circuit (27, 29, 31, 61) responsive to the filtered DC to DC converter voltage output for controlling the impedance matching circuit such that the filtered DC to DC converter output voltage is substantially constant.

## Claims

### Claim 1

A VHF DC to DC converter comprising:
resonant switching means connected between a supply voltage and ground, said switching means being driven with a periodic drive signal of a predetermined drive frequency;
an impedance matching circuit responsive to said resonant switching means;
rectifying means responsive to said impedance matching circuit;
filtering means responsive to said rectifying meas for providing a filtered DC to DC converter voltage output; and
a varactor diode circuit responsive to said filtered DC to DC converter voltage output for controlling said impedance matching circuit such that said filtered DC to DC converter output voltage is substantially constant.

### Claim 2 (depends on 1)

The DC to DC converter of claim 1 wherein said drive signal comprises a sinusoid.

### Claim 3 (depends on 1)

The DC to DC converter of claim 1 wherein said resonant switching means includes a transistor and a resonant circuit.

### Claim 4 (depends on 1)

The DC to DC converter of claim 1 wherein said bandpass filtering means is tuned to said predetermined drive frequency.

### Claim 5 (depends on 2)

The DC to DC converter of claim 2 wherein said varactor diode circuit includes amplifier means responsive to said filtered DC to DC converter voltage output, a low pass filter responsive to said amplifier means, and a varactor diode responsive to said low pass filter.