Improvement of Active-Input Current Mirrors Using Adaptive Biasing Technique

Dynamic CMOS current mirrors are used in a large variety of circuits as fundamental elements of analog design. Several topologies have been proposed over the years to improve their performances. Among these solutions, the active-input technique is intended to increase speed-power ratio and input compliance. However, it has been proven that this structure suffers from a restricted input-current dynamic. In this paper, we propose an enhancement of the active-input structure relying on adaptive biasing to overcome the input current range limitation at low cost in terms of power consumption, noise and silicon area. Theoretical analysis demonstrates the efficiency of the proposed enhancement. Then, an example circuit realized in AMS CMOS 0.18 µm technology at 1.8 V supply is validated by simulation results.