| 摘要 |
PURPOSE:To suppress phase distortion due to an excessive input signal by adding an AGC circuit operated while being not synchronized and preventing the effect of a disturbing wave. CONSTITUTION:The phase of an output signal of an amplifier 3a and that of a signal caused from a signal without distortion which is an output of a frequency converter 1 while being amplified and phase-shifted are compared, an AGC voltage is applied to a variable attenuator 2 via a low-pass filter 8b, a summing amplifier 14 and a switch 15 to control an output signal level of the amplifier 3a while the distortion is minimized. After a phase locked loop is closed, a lock-on signal changes over the switch 15 to supply a normal AGC (incoherent AGC) voltage to the variable attenuator 2. |
