Circuit configuration for setting the operating point of a radiofrequency transistor and amplifier circuit
AssigneeInfineon Technologies AG
InventorJosef-Paul Schaffer
Life of this patent
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Abstract
An amplifier circuit with a radiofrequency transistor has a circuit for setting the operating point. The setting circuit provides a base current for the radiofrequency transistor depending on the voltage drop across a resistor that is connected into the collector circuit of the radiofrequency transistor. The circuit has a differential element, which is fed by the supply voltage and compares the voltage drop across the resistor with a reference voltage. The base current is generated by a current source in dependence on the voltage difference. The circuit requires only a low supply voltage, with the result that the power consumed in the resistor is also low. The circuit can be implemented with a small number of components.
Claims9
A circuit configuration for setting an operating point of a radiofrequency transistor having a load current path and a control terminal, comprising:
- a terminal for a first supply potential and a terminal for a second supply potential;
- a measurement terminal for connection to a measuring resistor connected in series with the load current path of the radiofrequency transistor;
- an output terminal for connection to the control terminal of the radiofrequency transistor;
- a reference voltage source;
- a differential element having supply voltage terminals connected to said terminal for said first supply potential and to said terminal for said second supply potential, a first signal input connected to said reference voltage source, and a second signal input connected to said measurement terminal;
- a current source connected to and controllable by said differential element and connected to said output terminal;
- a first resistor connected to said terminal for the first supply potential and a second resistor connected to said terminal for the first supply potential;
- a current source connected to said terminal for the second supply potential;
- a current mirror circuit having an input path connected to said current source, an output path connected to said terminal for the first supply potential through said first resistor, and a control line coupling said input path to said output path;
- a transistor having a base connected to said control line and an emitter connected through said second resistor to said terminal for the first supply potential and to said measurement terminal.
Dependencies are inferred from the claim text.