LIMITER CIRCUIT

PURPOSE:To change a limit level by inserting a DC power supply in series with each of two diodes and controlling a voltage of the DC power supply externally. CONSTITUTION:An anode of a diode 109 and a cathode of a diode 110 are connected to an input of an amplifier 112. Moreover, a negative pole of a variable DC power supply 108 is connected to a cathode of the diode 109 and a positive pole of a variable DC power supply 111 is connected to an anode of the diode 110, and the positive pole of the variable DC power supply 108 and the negative pole of the variable DC power supply 111 are connected to a positive terminal of a bias power supply 105. The DC voltage of the variable DC power supplies 108, 111 is controlled by a signal inputted from a limit level input terminal 102. Since the variable DC power supplies 108, 111 are subject to voltage control so that the variable output voltage is equal to each other, the positive and the negative limit levels are set symmetrically.