Experimental Characterization of Millimeter-Wave SiGe-Integrated Avalanche Noise Sources for 4 K Cryogenic Applications

Abstract

Avalanche driven diodes have been traditionally used as electrical noise generator due to their capability of generating broadband random noise. Currently, no solutions have been reported to generate avalanche noise at cryogenic temperatures. This work represents a step toward addressing this gap. For the first time, we present the full characterization of two millimeter-wave noise sources (NSs) operating at cryogenic temperatures: the first based on the base-collector diode of an heterojunction bipolar transistor (HBT) driven into avalanche, while the second based on a p-i-n diode integrating the bias circuitry and the output attenuator. Both devices, fabricated using two different 130-nm silicon-germanium (SiGe) BiCMOS process and assessed as NSs at room temperature (RT), have now been demonstrated to operate reliably and efficiently for physical temperatures as low as 4.3 K. Both devices are measured over a complete cooling cycle with mid temperature points (i.e., 300, 70, 4.3) during cooling and warming cycle, to assess that no hysteresis or memory effect are present in their behavior. The reported excess noise ratio (ENR) of the HBT-based diode shows a maximum variation of about 1 and 0.5 dB for 2 and 4 mA bias currents, respectively, in the range of 1–40 GHz. For the same biasing ranges, the p-i-n NS showed a maximum variation of 2 dB at 30 GHz (on-chip attenuator included) resulting in a temperature sensitivity of about −0.007 dB/K. The reported results highlights the capability of such devices to realize a new class of integrated high performance cryogenic sources, opening the possibility to integrated in situ cryogenic calibrations.