Linear RF power amplifier
First Claim
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1. A push-pull RF power amplifier that comprises first and second high voltage field effect transistors each of which has a drain, a source, and a gate, said transistors each having a predetermined drain-source breakdown voltage;
- a supply of drain voltage coupled to the drains of said transistors, said supply famishing said drain voltage at a level that is below said drain-source breakdown voltage to create a safety margin between said drain-source breakdown voltage and a peak drain-source voltage, as defined by said drain voltage level, that is greater than the magnitude of said drain voltage level;
a signal input terminal to which an RF signal is applied;
an input balun transformer having an unbalanced input coupled to the signal input terminal and first and second balanced outputs coupled to the gates of the respective first and second transistors;
first and second bias circuits applying respective bias levels to the gates of said first and second transistors;
an output balun transformer having balanced inputs coupled to the drains of said first and second transistors respectively, and an unbalanced output; and
means coupling said unbalanced output to an RF output terminal.
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Abstract
A linear RF power amplifier employs push-pull pairs of high voltage mosfets. A minimum of transformers is employed, with an impedance matching transformer feeding an input balun supplying the input signal in push-pull to the gates of the mosfets. The drains are coupled to balanced legs of an output balun, followed by an output impedance matching transformer. Thermal sensors are employed for control of gate bias and also for control of drain voltage. The temperature sensors are mounted in the air inlet path and on the spreader plate of the heat sink. An aluminum or fiberglass strap is used to press the transistors against the spreader plate thereby ensuring good thermal contact with the transistor dies.
145 Citations
12 Claims
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1. A push-pull RF power amplifier that comprises first and second high voltage field effect transistors each of which has a drain, a source, and a gate, said transistors each having a predetermined drain-source breakdown voltage;
- a supply of drain voltage coupled to the drains of said transistors, said supply famishing said drain voltage at a level that is below said drain-source breakdown voltage to create a safety margin between said drain-source breakdown voltage and a peak drain-source voltage, as defined by said drain voltage level, that is greater than the magnitude of said drain voltage level;
a signal input terminal to which an RF signal is applied;
an input balun transformer having an unbalanced input coupled to the signal input terminal and first and second balanced outputs coupled to the gates of the respective first and second transistors;
first and second bias circuits applying respective bias levels to the gates of said first and second transistors;
an output balun transformer having balanced inputs coupled to the drains of said first and second transistors respectively, and an unbalanced output; and
means coupling said unbalanced output to an RF output terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 11, 12)
- a supply of drain voltage coupled to the drains of said transistors, said supply famishing said drain voltage at a level that is below said drain-source breakdown voltage to create a safety margin between said drain-source breakdown voltage and a peak drain-source voltage, as defined by said drain voltage level, that is greater than the magnitude of said drain voltage level;
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9. A push-pull RF power amplifier that comprises first and second high voltage field effect transistors each of which has a drain, a source, and a gate;
- a supply of drain voltage coupled to the drains of said transistors;
a signal input terminal to which an RF signal is applied;
an input impedance matching transformer having a high impedance input coupled to said signal input terminal and a low impedance output;
an input balun transformer having an unbalanced input coupled to the low impedance output of said input matching transformer and first and second balanced outputs coupled to the gates of the respective first and second transistors;
first and second bias circuits applying respective bias levels to the gates of said first and second transistors;
an output balun transformer having balanced inputs coupled to the drains of said first and second transistors respectively, and an unbalanced output;
an output transformer having a low impedance input coupled to said unbalanced output and a high impedance output coupled to an RF output terminal; and
a reversing transformer having first and second windings, each winding having a first terminal connected to the drain of a respective one of the first and second transistors, and a second terminal connected to said supply of drain voltage. - View Dependent Claims (10)
- a supply of drain voltage coupled to the drains of said transistors;
Specification
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Current AssigneeMKS Instruments Incorporated
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Original AssigneeENI Technology, Inc.
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InventorsReyzelman, Leonid, Chawla, Yogendra K.
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Primary Examiner(s)MOTTOLA, STEVEN J
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Application NumberUS08/800,336Time in Patent Office389 DaysField of Search330/269, 330/276, 330/301US Class Current330/269CPC Class CodesH03F 1/301 in MOSFET amplifiers H03F1/...H03F 3/193 with field-effect devices H...H03F 3/211 using a combination of seve...H03F 3/265 with field-effect transisto...H03F 3/604 using FET's
