| 摘要 |
PURPOSE:To always bring a peak value of an input signal within the operating range of a diode by providing a transmission power detection section whose threshold level is varied by the change in a bias voltage in a transmission power control circuit of a transmitter so as to apply a reverse bias circuit in response to the transmission power for a diode for the detection. CONSTITUTION:A bias voltage variable section 11 generates a bias voltage corresponding to a switching signal 12 and reverse-biases the diode 5 via a choke coil 8. The relation between a reverse bias voltage and a detection characteristic of the diode 5 is as shown in figure. Thus, in varying a bias voltage uB, it is possible to set the peak value of the input signal to an optional operating point of the diode and the DC output voltage is set to an optional value. Thus, even when the transmission power, that is, the amplitude of the input signal I is changed, the bias voltage uB is selected to set the peak value of the input signal to the same operating point of the diode to obtain the DC output voltage of the sample level.
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