| 摘要 |
A transmitter has a loop switch (132) and a feedback switch (127), which are operated by a control circuit (134). An unamplified value is obtained by connecting a cartesian demodulator (126) with the input to a power amplifier (118), applying a fixed baseband signal level to the input of the cartesian modulator, and measuring the output level of the cartesian demodulator. An amplified value is obtained by connecting the output of the power amplifier to the cartesian demodulator, again applying a fixed baseband signal level, and measuring the output of the demodulator. The amplified and unamplified values are compared by the control circuit, and the power amplifier gain is adjusted by varying the gain adjust signal (138), if necessary.
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