Design of high-speed and low-power finite-word-length PID controllers

ASIC or FPGA implementation of a finite wordlength PID controller requires a double expertise: in control system and hardware design. In this paper, we only focus on the hardware side of the problem. We show how to design configurable fixed-point PIDs to satisfy applications requiring minimal power consumption, or high control-rate, or both together. As multiply operation is the engine of PID, we experienced three algorithms: Booth, modified Booth, and a new recursive multi-bit multiplication algorithm. This later enables the construction of finely grained PID structures with bit-level and unit-time precision. Such a feature permits to tailor the PID to the desired performance and power budget. All PIDs are implemented at RTL level as technologyindependent reusable IP-cores. They are reconfigurable according to two compile-time constants: set-point word-length and latency. To make PID design easily reproducible, all necessary implementation details are provided and discussed.