High performance electronically tunable log-domain current-mode PID controller

This research proposes a log-domain P (proportional) I (integral) D (derivative) controller whereby the bias currents are arbitrarily applied to the P, I and D components for independent or simultaneous electronic tuning and the subsequent improved response. In the study, the initial P, I and D circuits were individually realized using 17, 13 and 21 bipolar transistors, and the final PID controller required 62 bipolar transistors including the biasing circuits and a multiple-output current buffer. The proposed PID controller was operational on a dual power supply of +/- 1.5 V, with the wide-range tunability up to three decades without the circuit topology alteration. Additionally, simulations were carried out with the individual P, I, D circuits and PID controller to verify the performance (i.e. tunability and the response time) and the simulation results compared with the existing PID schemes. Importantly, the simulation results of the PID controller are in good agreement with the theoretical PID functions.