In this study, a new CFOA-based PID controller circuit is designed and implemented by a systematic approach employing signal-flow graph theory which is a powerful tool for active circuit design. The proposed circuit has independently adjustable PID parameters (K-P, K-I, K-D) which are independently controlled by only one passive element. Having high input and low output impedances, it has the ability to cascade with other circuits. The proposed PID circuit is examined in a closed-loop control system with an example plant circuit. Mathematical analyses are performed and discussed. The PID controller is realized by using commercially available integrated circuit elements, and results are given to demonstrate the performance of the proposed PID controller.