High frequency, high voltage MOSFET isolation amplifier

• US 4,667,144 A
• Filed: 06/03/1986
• Issued: 05/19/1987
• Est. Priority Date: 06/03/1986
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Jones, Franklin B., Milberger, Walter E.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): Jones, Judson H.
• Application Number:
  US06/870,045
• Time in Patent Office: 350 Days
• Field of Search: 363/16, 323/271, 323/272, 323/274, 307/270, 307/571, 330/207 A, 330/251
• US Class Current: 323/271
• CPC Class Codes: G05F 1/561 Voltage to current converters amplifiers H03F
• CPC Class Codes: H03F 1/3205 in field-effect transistor amplifiers
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03F 3/3001 with field-effect transistors

Abstract

A MOSFET isolation amplifier apparatus to allow stable high frequency linear operation of MOSFET power stages and to provide precise regulation of a load current through a magnetic yoke load. Variations of transfer characteristics and input parameters in the MOSFET power stages are corrected by use of a feedback signal which is generated in a current sense resistor by the load current. Such a power stage allows the implementation of isolation amplifiers which can provide high power high frequency linear regulation at elevated voltages and currents.

Claims

1. A high frequency, high voltage MOSFET isolation amplifier apparatus comprising in combination:

a current control amplifier to receive a current command signal at its non-inverting input, said current control amplifier providing a current signal;

a modulating means operatively connected to said current control amplifier to receive said current signal, said modulating means modulating said current signal at a predetermined frequency to provide a control signal, said modulation means including an isolation means,

an operational amplifier means operatively connected to said modulating means to receive said control signal therefrom, said operational amplifier means providing a current control signal, said operational amplifier means floating with respect to ground,

a plurality of power MOSFET devices operatively connected to said operational amplifier means to receive said current control signal, said power MOSFET devices connected between a plus and minus high voltage power supply, said power MOSFET devices providing a load current,

an inductive load means operatively coupled to said power MOSFET devices to receive said load current, and,

a feedback means connected between said inductive load means and ground, said feedback means providing a feedback signal, said feedback signal being applied to the inverting input of said current control amplifier.

2. A high frequency, high voltage MOSFET isolation amplifier apparatus as described in claim 1 wherein said isolation means comprises a transformer coupling means.

3. A high frequency, high voltage MOSFET isolation amplifier apparatus as described in claim 1 wherein said operational amplifier means comprises a low impedance drive means.

4. A high frequency, high voltage MOSFET isolation amplifier apparatus as described in claim 1 wherein said inductive load means comprises a magnetic yoke.

5. A high frequency, high voltage MOSFET isolation amplifier apparatus as described in claim 1 wherein said plurality of power MOSFET devices comprise two power MOSFETs in series.

6. A high frequency, high voltage MOSFET isolation amplifier apparatus as described in claim 1 said predetermined frequency comprises a 10 MHz clock signal.