The invention relates to current mirror circuits in which an input current is reproduced in an output circuit. Thus, a current sink can be mirrored to act as a current source with both being referenced to a common power supply rail. The prior art circuits typically employ a diode to pass the input current which then must operate at least one V.sub.BE from the diode power supply rail. This places a constraint on the dynamic range of the circuit that can be severe at low power supply voltages.