Transmitter power varying device having a bypass line for a power amplifier
First Claim
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1. A transmitter power varying device comprising:
- a variable gain amplifier for amplifying a transmission signal with a variable gain;
a power amplifier for amplifying the transmission signal which is to be transmitted from an antenna;
a bypass line provided parallel with the power amplifier; and
first and second high-frequency signal changeover switches respectively provided upstream and downstream of the power amplifier and the bypass line, for causing the transmission signal to go through the bypass line while bypassing the power amplifier in response to an output power of the transmission signal being reduced below a first threshold value;
wherein the gain of the variable gain amplifier is increased to compensate for a gain reduction due to bypassing of the power amplifier.
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Abstract
A transmitter section of a mobile telephone set of a cellular telephone system includes a high-frequency signal oscillator, a modulator, a variable gain amplifier, a power amplifier, an antenna duplexer, and an antenna. Two high-frequency signal changeover switches are respectively provided upstream and downstream of the power amplifier. In transmitting a signal at a low output power, the power amplifier is turned off and the two changeover switches cause a high-frequency signal to go through a bypass line, that is, bypass the power amplifier. Thus, transmitter power control with a wide dynamic range can be attained while the power consumption is greatly reduced.
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Citations
16 Claims
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1. A transmitter power varying device comprising:
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a variable gain amplifier for amplifying a transmission signal with a variable gain; a power amplifier for amplifying the transmission signal which is to be transmitted from an antenna; a bypass line provided parallel with the power amplifier; and first and second high-frequency signal changeover switches respectively provided upstream and downstream of the power amplifier and the bypass line, for causing the transmission signal to go through the bypass line while bypassing the power amplifier in response to an output power of the transmission signal being reduced below a first threshold value; wherein the gain of the variable gain amplifier is increased to compensate for a gain reduction due to bypassing of the power amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A transmitter power varying device comprising:
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a variable gain amplifier for amplifying a transmission signal with a variable gain; a power amplifier for amplifying the transmission signal which is to be transmitted from an antenna; a quarter-wavelength line provided parallel with the power amplifier; and a high-frequency signal changeover switch provided upstream or downstream of the power amplifier and the quarter-wavelength line, for causing the transmission signal to go through the quarter-wavelength line while bypassing the power amplifier in response to an output power of the transmission signal being reduced below a threshold value; wherein the gain of the variable gain amplifier is increased to compensate for a gain reduction due to bypassing of the power amplifier.
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16. A transmitter power varying device comprising:
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a variable gain amplifier for amplifying a transmission signal with a variable gain; a power amplifier for amplifying the transmission signal which is to be transmitted from an antenna; a bypass line provided parallel with the power amplifier; first and second high-frequency signal changeover switches respectively provided upstream and downstream of the power amplifier and the bypass line, for causing the transmission signal to go through the bypass line while bypassing the power amplifier, reducing a power of the transmission signal below a first threshold value; an isolator provided in the bypass line; and a circulator that is connected to an output side of the isolator and to an output side of the power amplifier via the second high-frequency signal changeover switch, wherein the second high-frequency signal changeover switch is so constructed as to selectively connect the output side of the isolator to the output side of the power amplifier or a ground side via the circulator; wherein the gain of the variable gain amplifier is increased to compensate for a gain reduction due to bypassing of the power amplifier.
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Specification