Design of Mixed-Mode Analog PID Controller with CFOAs

Area of Science:

• Electronics Engineering
• Control Systems
• Analog Circuit Design

Background:

• Proportional-Integral-Derivative (PID) controllers are fundamental in control systems.
• Current-Feedback Operational Amplifiers (CFOAs) offer advantages in high-frequency analog circuit design.
• Mixed-mode operation in controllers allows for versatile signal processing.

Purpose of the Study:

• To propose a novel mixed-mode PID controller circuit.
• To demonstrate the controller's capability in four distinct operating modes: voltage, trans-admittance, current, and trans-impedance.
• To evaluate the controller's performance and its impact on a closed-loop control system.

Main Methods:

• Design and mathematical analysis of a mixed-mode PID controller using three CFOAs, four resistors, and two capacitors.
• Implementation of the controller using the AD844 CFOA IC.
• Simulation of the controller and a closed-loop control system incorporating a mixed-mode second-order low-pass filter.

Main Results:

• The proposed circuit topology successfully implements PID control in four mixed modes.
• The controller exhibits low power consumption (0.348 W) and good temperature stability (<0.2% variation).
• Monte Carlo analysis shows minimal gain deviation (≤7.72%), and the closed-loop system demonstrates a 43% faster rise/peak time and low steady-state errors.

Conclusions:

• The proposed mixed-mode PID controller is a versatile and efficient solution for various control applications.
• The controller significantly improves the dynamic performance of closed-loop systems.
• The design is validated through simulations, confirming its practical applicability.