A 60-GHz SiGe Radiometer Calibration Switch Utilizing a Coupled Avalanche Noise Source

This letter presents a novel implementation of a V-band single-pole double-throw switch that facilitates the internal calibration of radiometers by integrating an ambient noise source and an avalanche noise source. The switch is implemented in a 0.13-μm SiGe bipolar-CMOS (BiCMOS) process and uses a shunt topology with λ/4 directional couplers that inject noise from the avalanche source. The avalanche source is implemented using the collector-base junction of a SiGe heterojunction bipolar transistor (HBT) and attains a measured excess noise ratio of 18.7 dB at 60 GHz. The switch achieves a midband insertion loss of 2.0 dB and an isolation of 22 dB at 60 GHz. An excess input-referred noise temperature of 620 K is added with the noise source ON. To the best of our knowledge, this is the first avalanche noise source using a diode-configured SiGe HBT and the first monolithic two-reference switch for calibrating millimeter-wave radiometers.