RF driven gate bias

• US 5,087,893 A
• Filed: 12/18/1989
• Issued: 02/11/1992
• Est. Priority Date: 12/18/1989
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Petersen, Michael W., Fischbach, Clark D.
• Primary Examiner(s): MOTTOLA, STEVEN J
• Application Number:
  US07/452,172
• Time in Patent Office: 785 Days
• Field of Search: 330/123, 330/136, 330/140, 330/277, 330/296, 330/297, 333/116, 333/128, 455/127, 323/299, 323/301, 323/303
• US Class Current: 330/296
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04

Abstract

A circuit for providing DC bias voltage to an RF power amplifier transistor where the DC bias voltage is derived from the RF input signal.

Claims

1. A circuit for providing bias voltage to at least one amplifier transistor having an RF input signal, the circuit comprising:

RF power divider means for providing a sample of the RF input signal;

rectifier means for converting the sample into a DC voltage;

regulator means responsive to the rectifier means for providing the bias voltage and limiting amplitude to ensure a relatively constant bias voltage over a relatively wide range of RF input signal amplitudes.

2. The circuit in accordance with claim 1, wherein said at least one amplifier transistor is a MOSFET.

3. The circuit in accordance with claim 2, wherein the MOSFET is an enhancement mode MOSFET.

4. The circuit in accordance with claim 1, wherein the RF power divider means comprises a tapped microstrip transmission line.

5. A method for providing bias voltage to at least one amplifier transistor having an RF input signal, the method comprising:

(a) providing a sample of the RF input signal;

(b) converting the sample into a DC voltage; and

(c) regulating the DC voltage to provide the bias voltage and to ensure a relatively constant bias voltage over a relatively wide range of RF input signal amplitudes.

6. For a MOSFET RF power amplifier stage having an RF input signal, a method for providing an RF driven gate bias voltage derived from the RF input signal, the method comprising:

(a) sampling the RF input signal to provide a sampled signal;

(b) rectifying the sampled signal to provide a pulsating DC voltage;

(c) filtering the pulsating DC voltage to provide a filtered DC voltage; and

(d) regulating the filtered DC voltage to provide the RF driven gate bias voltage.