Low Phase Noise 92 GHz Phase-Locked Source for Passive Millimeter Wave Imaging System

Abstract

This paper presents a low phase noise 92 GHz phase-locked source module with four output ports. This millimeter wave source is used as local oscillators (LO) in a passive millimeter wave imaging system. It achieves a -90.46 dBc/Hz (at 10 kHz offset 92 GHz carrier frequency) phase noise performance, the spur level is lower than -60 dBc. A well matched low insertion loss waveguide four-way power divider is designed, and its output power is more than 12 mW at each output port. In addition, analysis indicates that the wideband LO noise performance is critical in passive millimeter wave imaging systems. Therefore, a transmission type cylinder cavity is arranged before the power divider, which can effectively reduce the wide band noise of the millimeter wave source.