the collector of the transistor q 11 and the node common to these collectors is connected to the input of a current mirror 7 whose output also constitutes the output of the full wave rectifier for a positive half cycle relative to the reference voltage v r of the signal voltage on the input 2 the transistor q 11 is conductive and feeds the current through the resistor r 1 to the current mirror 7 the diode q 15 then pulls down the potential on the output of the current source 4 so far that the transistors q 8 and q 9 are cut off during the positive half cycle during the negative half cycle of the signal voltage on the input the potential on the output of the current source 4 changes exactly to such an extent that the entire signal current flowing through the resistor r 1 can flow to the current source 4 via the transistor q 8 as a result of this a current of the same value will flow to the current mirror 7 via the transistor q 8 during the negative half cycle the input current consequently flows into the unit 3 which supplies an equal output current consequently the unit 3 in conjunction with the current source 4 and the associated circuitry acts as a current mirror it is therefore referred to as a current mirror although considered by itself it does not constitute a conventional current mirror the current.