High frequency power amplifier, transmitter and mobile communication terminal using the power amplifier
First Claim
Patent Images
1. A high frequency power amplifier for use in a high frequency mobile communication terminal, comprising:
- at least one amplification stage that amplifies an input signal from a gain variable amplifier, wherein the at least one amplification stage includes an output amplification stage which comprises a transistor and constitutes a final stage of the at least one amplification stage;
an output matching circuit that is connected to an output side of the final stage of the at least one amplification stage;
a first detection unit that detects a voltage amplitude at a node between the transistor of the final stage of the at least one amplification stage and the output matching circuit, and outputs the voltage amplitude as a first signal of gain control information of the gain variable amplifier; and
a supply voltage detector unit that detects a supply voltage being supplied to the final stage of the at least one amplification stage and outputs the supply voltage as a second signal of the gain control information of the gain variable amplifier,wherein the gain variable amplifier is controlled based on the gain control information so as to limit a gain of the gain variable amplifier upon the voltage amplitude exceeding a predetermined threshold voltage.
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Abstract
A high frequency power amplifier maintains an excellent linearity regardless of a fluctuation of a load impedance and is downsized. The high frequency power amplifier detects an AC voltage amplitude at an output terminal of a final amplification stage transistor, and suppresses an input signal amplitude of a power amplifier when the voltage amplitude exceeds a predetermined threshold value.
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Citations
17 Claims
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1. A high frequency power amplifier for use in a high frequency mobile communication terminal, comprising:
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at least one amplification stage that amplifies an input signal from a gain variable amplifier, wherein the at least one amplification stage includes an output amplification stage which comprises a transistor and constitutes a final stage of the at least one amplification stage; an output matching circuit that is connected to an output side of the final stage of the at least one amplification stage; a first detection unit that detects a voltage amplitude at a node between the transistor of the final stage of the at least one amplification stage and the output matching circuit, and outputs the voltage amplitude as a first signal of gain control information of the gain variable amplifier; and a supply voltage detector unit that detects a supply voltage being supplied to the final stage of the at least one amplification stage and outputs the supply voltage as a second signal of the gain control information of the gain variable amplifier, wherein the gain variable amplifier is controlled based on the gain control information so as to limit a gain of the gain variable amplifier upon the voltage amplitude exceeding a predetermined threshold voltage. - View Dependent Claims (2, 3, 4, 5)
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6. A transmitter for use in a high frequency mobile communication terminal, comprising:
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a high frequency power amplifier; and a control unit, wherein the high frequency power amplifier comprises; at least one amplification stage that amplifies an input signal from a gain variable amplifier, wherein the at least one amplification stage includes an output amplification stage which comprises a transistor for amplification and constitutes a final stage of the at least one amplification stage; an output matching circuit that is connected to an output side of the final stage of the at least one amplification stage; a first detection unit that detects a voltage amplitude at a node between the transistor of the final stage of the at least one amplification stage and the output matching circuit, and outputs the voltage amplitude as a first signal of gain control information of the gain variable amplifier; and a supply voltage detector unit that detects a supply voltage being supplied to the final stage of the at least one amplification stage of the power amplifier, wherein the control unit has a function of controlling the gain of the gain variable amplifier according to the first signal of gain control information from the first detection unit and a second signal of gain control information from the supply voltage detector unit, and wherein the control unit monitors the voltage amplitude of the first signal of gain control information and generates a control signal for limiting a gain of the gain variable amplifier upon the voltage amplitude exceeding a predetermined threshold voltage. - View Dependent Claims (7, 8, 9, 10)
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11. A mobile communication terminal, comprising:
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a base band circuit having a limiter that determines a maximum transmit power of the mobile communication terminal; a transmit variable gain amplifier; a high frequency power amplifier that amplifies a transmit signal; a front end module; and an antenna, wherein the base band circuit has a function of supplying a transmit gain control signal that is generated by a terminal control unit to the transmit variable gain amplifier through the limiter, wherein the high frequency power amplifier includes a high frequency power amplifier circuit that amplifies a high frequency signal, an output matching circuit, a bias control circuit, a first detection unit that detects a voltage amplitude at a node between a transistor of a final stage of at least one amplification stage of the high frequency power amplifier circuit and the output matching circuit, and outputs the voltage amplitude as a first signal of gain control information of the transmit gain variable amplifier, and a supply voltage detector unit that detects a supply voltage being supplied to the final stage of the at least one amplification stage and outputs the supply voltage as a second signal of the gain control information of the transmit gain variable amplifier, wherein the at least one amplification stage of the high frequency power amplifier circuit amplifies an input signal from a gain variable amplifier, wherein the at least one amplification stage includes an output amplification stage which constitutes the final stage of the amplification stage, wherein the output matching circuit is connected to an output side of the final stage of the at least one amplification stage, wherein the front end module includes a changeover switch for transmission and reception, an output detector circuit that detects an output level of the transmit signal which is outputted from the high frequency power amplifier, and an automatic power control circuit that generates an output control signal with respect to the gain variable amplifier, wherein there are provided functions of generating a control current with respect to the bias control circuit in the base band circuit, and generating transmit level adjustment information for monitoring a quality of a signal which is attributable to a positional relationship between the mobile communication terminal and a base station and adjusting a transmit level in the transmit variable gain amplifier, wherein there is provided a function of changing a limit value of the limiter on the basis of the transmit level adjustment information and the gain control information, and wherein the gain variable amplifier is controlled based on the gain control information so as to limit a gain of the gain variable amplifier upon the voltage amplitude exceeding a predetermined threshold voltage. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification