CCAT: Multi-Rate DSP for Sub-mm Astronomy: Polyphase Synthesis Filter Bank on FPGA for Enhanced MKID Readout

TL;DR

This paper presents a novel FPGA-based polyphase synthesis filter bank for MKID readout in submillimeter astronomy, enabling real-time, scalable, and high-performance signal processing on advanced RFSoC hardware.

Contribution

It introduces an overlap-channel polyphase synthesis filter bank on FPGA that improves bandwidth, dynamic range, and MKID tracking for next-generation astronomical instruments.

Findings

Achieves high SNR with the new filter bank design

Demonstrates real-time, dynamic signal generation capabilities

Shows scalability and laboratory performance validation

Abstract

The next-generation mm/sub-mm/far-IR astronomy will in part be enabled by advanced digital signal processing (DSP) techniques. The Prime-Cam instrument of the Fred Young Submillimeter Telescope (FYST), featuring the largest array of submillimeter detectors to date, utilizes a novel overlap-channel polyphase synthesis filter bank (OC-PSB) for the AC biasing of detectors, implemented on a cutting-edge Xilinx Radio Frequency System on Chip (RFSoC). This design departs from traditional waveform look-up-table(LUT) in memory, allowing real-time, dynamic signal generation, enhancing usable bandwidth and dynamic range, and enabling microwave kinetic inductance detector (MKID) tracking for future readout systems. Results show that the OC-PSB upholds critical performance metrics such as signal-to-noise ratio (SNR) while offering additional benefits such as scalability. This paper will discuss DSP design, RFSoC implementation, and laboratory performance, demonstrating OC-PSB's potential in submillimeter-wave astronomy MKID readout systems.