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FPGA-based Low-Latency Digital Servo for Optical Physics Experiments



Marco Pomponio, Archita Hati, Craig Nelson


We propose a general-purpose dual-channel field-programmable gate array (FPGA) based digital servo with a minimum latency around 200 ns. This servo implements a proportional, dual- integration and derivative (PIID) controller along with internal numerical controlled oscillators (NCO), a phase detector (PD) utilizing a fast in-phase and quadrature (I/Q) detection algorithm (80 ns), NCO modulator, network analyzer, auto-locker, ramp generator, and low pass filters. A web interface and/or python commands over TCP/IP allows full control and monitoring. The servo has been successfully used to lock Pound-Drever-Hall cavities, phase- locked loops and optical frequency combs. A simple experiment phase-locking two dielectric resonator oscillators (DRO) has been set up to demonstrate a 1 MHz closed-loop bandwidth.
Proceedings Title
IEEE IFCS-ISAF 2020 Conference Proceedings
Conference Dates
July 19-23, 2020
Conference Location
Keystone, CO, US
Conference Title
IEEE IFCS-ISAF 2020 Conference


automatic locking, digital phase detector, digital servo, DRO, FPGA, low-latency, optical frequency comb


Pomponio, M. , Hati, A. and Nelson, C. (2020), FPGA-based Low-Latency Digital Servo for Optical Physics Experiments, IEEE IFCS-ISAF 2020 Conference Proceedings, Keystone, CO, US, [online], (Accessed April 20, 2024)
Created October 22, 2020, Updated April 25, 2023