Tunable PID controller based on log-domain circuits

Current-mode proportional plus integral plus derivative (PID) controller based on log-domain concept is presented in this paper. The parameters of P, I, and D blocks can be independently controlled through bias currents. Only grounded capacitors are employed as a passive element for achieving the time-constant of I and D controllers. In each block of I and D controllers are easily constructed by using 10 bipolar transistors and a grounded capacitor except P controller uses only 4 bipolar transistors without any resistors. Thus, it is suitable for integrated circuits realization. Single power supply voltage 2.5V is used. The characteristics of PID are simulated is by SPICE. The demonstrated results are in good agreement with the theoretical expectations.