Abstract: Circuitry for use in the current control loop of switched mode power supplies which in a first embodiment increases the a-c gain of that loop. In a second embodiment the circuit rejects common mode noise in the loop. In this embodiment the secondary of the transformer used to sense current in the power switching means of the circuit is made up of two windings in series which are wound bifilar with respect to each other. The d-c signal representative of the current in the switching means is taken between one end of the secondary and the center point of the series connection. In a third embodiment the circuit provides a relatively accurate representation of low current in the power switching device. In this embodiment the circuit uses at least one compensation means in series with resistive means connected across the secondary of the transformer to compensate for the turn-on voltage of the at least one diode used in the peak charging portion of the circuit.