OUTPUT POWER CONTROL CIRCUIT AND TRANSMISSION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To absorb temperature fluctuation and characteristic fluctuation due to a secular change and to hold output power to be constant by generating a voltage difference between the output of a part to be controlled, which is the control object of output power, and respective outputs obtained by square- detecting signals branched at an input terminal and supplying differential voltage as the gain control voltage of the part to be controlled. SOLUTION: First and second couplers 1-1 and 1-2 branch the input/output power of a part to be controlled at a prescribed rate and supply them to first and second square detection circuits 4-1 and 4-2. The output voltages are proportional to the input/output voltages of the part to be controlled. Output voltages VIN and Vout are obtained through first and second logarithm amplifiers 5-1 and 5-2 and they are inputted to a differential generation circuit 7. The difference of both voltages is generated and differential voltage VREF at a prescribed temperature is supplied to the inversion input terminal of a control voltage generation circuit 8 and to a non-inversion input terminal. The output is sent to a variable 4 gain amplifier 3 and a gain is set to a prescribed value when differential voltage is equal to voltage VREF.