A 1 GHz 64-Channel High-Level Digital Correlator for Aperture Synthesis Passive Millimetre-Wave Security Imager

Abstract

A new generation of aperture synthesis passive millimetre-wave imager is being developed for security screening using 4096 element antennas with 3.5 GHz bandwidth, enabling high radiometric sensitivity at a video frame rate. This paper proposed a high performance digital correlator deployed in such system that uses integrated connectors to input a 1 GHz bandwidth, 32 I/Q input signals from IF processors. The proposed correlator is implemented up to 2080 of 2-bit/4-level (2B/4L) correlation units in a field programmable gate array (FPGA). A novel structure suitable for an FPGA is developed, occupying less than 11% of hardware resource utilisation, allowing a maximum clock frequency of over 289 MHz. A test system is built to verify the design, and a correlation efficiency above 99.4% is observed at the proposed interval, which outperforms other state-of-the-art zero-lag digital cross-correlators.