A many-channel FPGA control system

Area of Science:

• Experimental Physics
• Control Systems Engineering
• Embedded Systems Design

Background:

• Advanced experimental control systems are crucial for high-precision scientific research.
• Existing systems often face limitations in channel count, speed, and resource efficiency.
• Field-programmable gate arrays (FPGAs) offer a flexible platform for developing high-performance control solutions.

Purpose of the Study:

• To develop and characterize a many-channel experiment control system utilizing FPGA technology.
• To demonstrate the system's capability in managing multiple high-speed servo loops and complex waveform generation.
• To present efficient digital filter implementations for resource-constrained FPGA environments.

Main Methods:

• Implementation of a custom FPGA-based control system with high-resolution analog I/O and digital interfaces.
• Development of low-latency (30 ns) infinite-impulse-response (IIR) proportional-integral-differential filters using bit-shifts and additions.
• Integration of a touchscreen interface for real-time experiment monitoring and control.
• Demonstration of applications including laser locking, temperature servos, and arbitrary waveform generation.

Main Results:

• The FPGA system provides 10 analog input (100 MS/s, 16-bit) and 14 analog output (100 MS/s, 16-bit) channels.
• Support for up to ten servo loops with 155 ns latency and MHz bandwidths, plus additional lower-bandwidth servos.
• Demonstrated IIR filters achieve 30 ns latency, conserving FPGA resources compared to multiplier-based designs.
• Successful implementation of Hänsch-Couillaud laser locks, variable duty cycle temperature servos, and synchronized arbitrary waveform generation.

Conclusions:

• The developed FPGA system provides a powerful and versatile platform for high-channel-count, high-speed experiment control.
• Efficient IIR filter designs enable complex control tasks on a single FPGA, reducing hardware requirements.
• The system's flexibility and performance are suitable for a range of demanding scientific applications.