Matching Considerations for Bidirectional Current Mirrors

This paper elaborates in detail which matching dynamics occur when mirroring bidirectional currents. Formulas for the matching error of bidirectional current mirrors are deduced from the unidirectional case. Simulation results confirm these calculations and verify that the matching degradation due to the bidirectional nature is stronger than the degradation due to the transistor coming into weak inversion. Depending on whether or not calibration is acceptable the paper states suitable design considerations.