High frequency power amplifier circuit and electric component for high frequency power amplifier
First Claim
1. A semiconductor integrated circuit for high frequency power amplifier comprising:
- a power amplifier circuit including two or more transistors for amplification connected in cascade to amplify a high frequency signal to be transmit;
a detection circuit which detects an input signal to a last-stage transistor of the power amplifier circuit, generates a voltage corresponding to the amplitude of the input signal, and supplies the voltage to a control terminal of the last-stage transistor; and
a bias circuit which generates bias voltages to set desired idle currents to flow through the transistors for amplification respectively, wherein the last-stage transistor and elements constituting the detection circuit are formed on a same semiconductor substrate, and the detection circuit receives the bias voltage which is given to the last-stage transistor and an AC component of the input signal, generates a voltage corresponding to the level of the bias voltage and the AC signal level, and supplies the voltage to the control terminal of the last-stage transistor.
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Accused Products
Abstract
In a high frequency power amplifier circuit in which bias voltages are applied to the transistors for amplification by current mirroring, this invention enables preventing waveform distortion near the peak output power level by allowing sufficient idle currents to flow through the transistors for amplification, while enhancing the power efficiency in a low output power region. The power amplifier includes a detection circuit comprising a transistor for detection which receives the AC component of an input signal to the last-stage transistor for amplification at its control terminal, a current mirror circuit which mirrors current flowing through that transistor, and a current-voltage conversion means which converts current flowing in the slave side of the current mirror circuit into a voltage. In the detection circuit, a voltage from a bias circuit for generating the bias voltages for the transistors for amplification is applied to the control terminal of the transistor for detection and output of the detection circuit is applied to the control terminal of the last-stage transistor for amplification.
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Citations
10 Claims
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1. A semiconductor integrated circuit for high frequency power amplifier comprising:
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a power amplifier circuit including two or more transistors for amplification connected in cascade to amplify a high frequency signal to be transmit;
a detection circuit which detects an input signal to a last-stage transistor of the power amplifier circuit, generates a voltage corresponding to the amplitude of the input signal, and supplies the voltage to a control terminal of the last-stage transistor; and
a bias circuit which generates bias voltages to set desired idle currents to flow through the transistors for amplification respectively, wherein the last-stage transistor and elements constituting the detection circuit are formed on a same semiconductor substrate, and the detection circuit receives the bias voltage which is given to the last-stage transistor and an AC component of the input signal, generates a voltage corresponding to the level of the bias voltage and the AC signal level, and supplies the voltage to the control terminal of the last-stage transistor. - View Dependent Claims (2, 3, 4, 10)
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5. A semiconductor integrated circuit for high frequency power amplifier comprising:
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a power amplifier circuit including two ore more transistors for amplification connected in cascade to amplify a high frequency signal to be transmit; and
a nonlinear amplifier circuit which makes flow an operating current in accordance with a predetermined bias voltage and in which output of a preceding-stage transistor of the power amplifier circuit is inputted, wherein the nonlinear amplifier circuit generates a voltage in accordance with a magnitude of the operating current and a magnitude of the output of the preceding-stage transistor and supplies the voltage to the control terminal of the last-stage transistor of the power amplifier circuit. - View Dependent Claims (6, 7, 8, 9)
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Specification