Stabilization circuit for transistor RF power amplifiers
AssigneeHarris Corporation
InventorJohn F. Davis, Jr.
Life of this patent
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Abstract
A stabilization circuit inhibits spurious oscillations of a Class C transistor power amplifier. A relatively large value resistor is connected in the base circuit of the amplifier transistor to inhibit the tendency of the amplifier to oscillate. A diode is added to the base circuit to prevent the possible failure of the transistor attendant to the use of the relatively high value resistor.
Claims11
A Class C amplifier of the type used in radio communications having a stabilization circuit for preventing spurious oscillations in the output signal of the amplifier and for reducing the chances of transistor failure due to changing load conditions, comprising:
- an amplifying transistor biased to operate in the Class C mode of operation;
- a circuit element connected between the base and emitter junctions of said amplifying transistor for inhibiting spurious oscillations in the transistor;
- and
- means responsive to the voltage across said circuit element for limiting the base voltage of said amplifying transistor to prevent transistor failure.
A method for stabilizing the operation of a Class C power amplifier by substantially inhibiting the spurious oscillations inherent to such an amplifier and by reducing the chances of failure due to changing load conditions, comprising the steps of:
- providing an element of resistance between the base and emitter junctions of a transistor biased to operate in a Class C mode of operation, to inhibit spurious oscillations in the output signal of said amplifier;
- and
- limiting the voltage which can be developed across said resistance element to a predetermined value to prevent said transistor from failing.
A stabilized Class C power transistor amplifier comprising:
- an amplifying transistor biased to operate in the Class C mode of operation;
- an impedance element having one terminal thereof connected to the base of said transistor;
- a resistor connected between the other terminal of said impedance element and the emitter of said transistor for inhibiting the inherent tendency of the transistor to oscillate;
- and
- a diode connected in parallel with said resistor such that said diode will become forward biased when the voltage across said resistor reaches a predetermined value less than the voltage required to bias said transistor to a point of failure.
A Class C amplifier of the type used in radio communications having a stabilization circuit for preventing spurious oscillations in the output signal of the amplifier and for reducing the chances of transistor failure due to changing load conditions, comprising:
- an amplifying transistor biased to operate in the Class C mode of operation;
- means for applying a base bias voltage to said amplifying transitor sufficient to inhibit spurious oscillations in the transistor;
- and
- means responsive to said base voltage for limiting the base voltage of said amplifying transistor to prevent transistor failure.
Dependencies are inferred from the claim text.