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

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.