US 8,031,003 B2Granted

Solid-state RF power amplifier for radio transmitters

OwnerSteven M. Dishopinventor

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Abstract

An RF power amplifier includes a push-pull amplifier having field effect transistors. Temperature compensating bias circuitry provides a temperature compensated bias voltage to the transistors for decreasing the bias voltage thereof as temperature increases. The temperature compensating bias circuitry includes a temperature sensor generating a temperature signal. A first amplifier provides a first temperature dependent voltage based on the temperature signal. A second amplifier provides a second temperature dependent voltage based on the temperature signal. The first and second temperature dependent voltages change at substantially the same rate in response to the temperature signal. A potentiometer receives the first and second temperature dependent voltages such that a voltage across the potentiometer remains substantially constant when the first and second temperature dependent voltages change. An output of the bias circuitry is connected to at least one of the transistors and supplies the temperature compensated bias voltage to the at least one of the transistors.

Claims30

Dependent claims

An RF power amplifier, comprising:

a first field effect transistor:
having a first gate, a first source, and a first drain,
having an output power rating of at least 200 watts, and
operating with a drain-to-source voltage that is greater than 50 VDC;
a second field effect transistor:
having a second gate, a second source, and a second drain,
having an output power rating of at least 200 watts, and
operating with a drain-to-source voltage that is greater than 50 VDC;
wherein said transistors are configured as a push-pull amplifier;
an RF signal input;
an input transformer connected to the RF signal input, the input transformer having respective balanced outputs connected to the first gate and the second gate;
a broadband output transformer having a first balanced input connected to the first drain, and a second balanced input connected to the second drain, wherein the broadband output transformer has an input to output impedance ratio of 1:4, and further wherein at least some flux cancellation occurs within the broadband output transformer;
and
temperature compensating bias circuitry for providing a temperature compensated bias voltage to the first field effect transistor and the second field effect transistor for decreasing the bias voltage of the first field effect transistor and the second field effect transistor as transistor temperature increases, the temperature compensating bias circuitry comprising:
a temperature sensor generating a temperature signal;
a first amplifier having an output providing a first temperature dependent voltage based on the temperature signal;
a second amplifier having an output providing a second temperature dependent voltage based on the temperature signal, wherein the first temperature dependent voltage and the second temperature dependent voltage change at substantially the same rate in response to the temperature signal;
and
a potentiometer connected to the output of the first amplifier and the output of the second amplifier such that a voltage across the potentiometer remains substantially constant when the first temperature dependent voltage and the second temperature dependent voltage change;
and
a bias output connected to at least one of the first field effect transistor and the second field effect transistor and supplying the temperature compensated bias voltage to the at least one of the first field effect transistor and the second field effect transistor.

18 more elements

An RF power amplifier, comprising:

a first plurality of field effect transistors having directly interconnected drains and respective output power ratings of at least 100 watts;
a second plurality of field effect transistors having directly interconnected drains and respective output power ratings of at least 100 watts;
wherein said transistors operate with a drain-to-source voltage that is greater than 50 VDC, and
wherein the first plurality of field effect transistors and the second plurality of field effect transistors together form a push-pull amplifier having an output power rating of at least 400 watts;
an RF signal input;
an input transformer connected to the RF signal input, the input transformer having respective balanced outputs connected to gates of the first plurality of field effect transistors and gates of the second plurality of field effect transistors;
and
a broadband output transformer having a first balanced input connected to the drains of the first plurality of field effect transistors, and a second balanced input connected to the drains of the second plurality of field effect transistors, wherein the broadband output transformer has an input to output impedance ratio of 1:4, and further wherein at least some flux cancellation occurs within the broadband output transformer;
and
temperature compensating bias circuitry for providing a temperature compensated bias voltage to the first plurality of field effect transistors and the second plurality of field effect transistors for decreasing the bias voltage of the first plurality of field effect transistors and the second plurality of field effect transistors as transistor temperature increases, the temperature compensating bias circuitry comprising:
a temperature sensor generating a temperature signal;
a first amplifier having an output providing a first temperature dependent voltage based on the temperature signal;
a second amplifier having an output providing a second temperature dependent voltage based on the temperature signal, wherein the first temperature dependent voltage and the second temperature dependent voltage change at substantially the same rate in response to the temperature signal;
and
a potentiometer connected to the output of the first amplifier and the output of the second amplifier such that a voltage across the potentiometer remains substantially constant when the first temperature dependent voltage and the second temperature dependent voltage change;
and
a bias output connected to at least one of the first plurality of field effect transistors and the second plurality of field effect transistors and supplying the temperature compensated bias voltage to the at least one of the first plurality of field effect transistors and the second plurality of field effect transistors.

14 more elements

An RF power amplifier, comprising:

a push-pull amplifier, the push-pull amplifier comprising a first field effect transistor and a second field effect transistor;
and
temperature compensating bias circuitry for providing a temperature compensated bias voltage to the first field effect transistor and the second field effect transistor for decreasing the bias voltage of the first field effect transistor and the second field effect transistor as transistor temperature increases, the temperature compensating bias circuitry comprising:
a temperature sensor generating a temperature signal;
a first amplifier having an output providing a first temperature dependent voltage based on the temperature signal;
and
a potentiometer connected to the output of the first amplifier such that a voltage across the potentiometer remains substantially constant when the first temperature dependent voltage changes;
and
a bias output connected to at least one of the first field effect transistor and the second field effect transistor and supplying the temperature compensated bias voltage to the at least one of the first field effect transistor and the second field effect transistor.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/714,609Filed 1 Mar 2010 · continuation in part
Priority: 17 May 2006
Published: US 2010/0156537 A124 Jun 2010
Granted: 4 Oct 2011
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

H03F 3/211
With semiconductor devices only: using a combination of several amplifiers
H03F 3/24
Power amplifiers, e.g. Class B amplifiers, Class C amplifiers: of transmitter output stages
H03F 3/265
Push-pull amplifiers; Phase-splitters therefor: with field-effect transistors only
H03F 3/3098
Two power transistors being controlled by the input signal: using a transformer as phase splitter

Family

Application60/801,006Us provisional application · filed 17 May 2006
Application60/747,662Us provisional application · filed 18 May 2006
Application11/749,786Parent of this continuation-in-part · filed 17 May 2007
US 2010/0156537 A1Pre-grant publication · published 24 Jun 2010
US 7,683,718 B2Parent of this continuation-in-part
US 2007/0285168 A1Published application
US 8,031,003 B2This patent

From the US filing history. Foreign family members aren’t listed.