Radio frequency power amplifier circuit
First Claim
Patent Images
1. A radio frequency power amplifier for receiving and power-amplifying an input signal for outputting, comprising:
- amplifying transistors in a plurality of stages;
a detection circuit that detects an output power; and
a protection circuit that controls to shunt a current flowing through a signal input terminal of at least one amplifying transistor disposed in a stage preceding a final stage out of said amplifying transistors in a plurality of stages according to a detector output of said detection circuit,wherein said protection circuit comprises a switch ON/OFF controlled according to a detector output from said detection circuit, andwherein a current flowing through a signal input terminal of said at least one amplifying transistor is shunted to a low potential power supply when said switch is ON.
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Abstract
A radio frequency power amplifier, having a first amplifying transistor 103-1 and a second amplifying transistor 103-2, comprises a detection circuit 101 that detects an output power and outputs a voltage according to the output power, and a protection transistor 102, controlled by an output of the detection circuit 101, for shunting a current flowing into the base terminal of the first amplifying transistor 103-1. The influence of a circuit for protecting against output load abnormalities on RF characteristics is suppressed.
14 Citations
21 Claims
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1. A radio frequency power amplifier for receiving and power-amplifying an input signal for outputting, comprising:
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amplifying transistors in a plurality of stages; a detection circuit that detects an output power; and a protection circuit that controls to shunt a current flowing through a signal input terminal of at least one amplifying transistor disposed in a stage preceding a final stage out of said amplifying transistors in a plurality of stages according to a detector output of said detection circuit, wherein said protection circuit comprises a switch ON/OFF controlled according to a detector output from said detection circuit, and wherein a current flowing through a signal input terminal of said at least one amplifying transistor is shunted to a low potential power supply when said switch is ON. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A radio frequency power amplifier for receiving and power-amplifying an input signal for outputting, comprising:
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amplifying transistors in a plurality of stages; a detection circuit that detects an output power; a protection circuit that controls to shunt a current flowing through a signal input terminal of at least one amplifying transistor disposed in a stage preceding a final stage out of said amplifying transistors in a plurality of stages according to a detector output of said detection circuit; and a matching circuit between a signal input terminal of at least one amplifying transistor out of said amplifying transistors in a plurality of stages and a signal output terminal of an amplifying transistor in a preceding stage of an input terminal receiving said input signal, wherein said protection circuit comprises a switch ON/OFF controlled according to a detector output from said detection circuit.
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Specification