Integrated noise sources (or hot loads) are essential to enable precise gain and noise figure Built-In Test Equipment (BITE) measurements. The present paper describes a millimeter-wave, solid-state noise source implemented in a standard, 130-nm Silicon-Germanium (SiGe) Bipolar-Complementary Metal Oxide Semiconductor (BiCMOS) process. This device is based on a p-i-n (varactor) diode that has two states: a cold state, when it is off, and an hot state when the diode is driven into avalanche breakdown. Two noise diodes with 10 and 20 square microns area have been fabricated and experimentally characterized. The measurements highlight a breakdown voltage is close to 10.7 V, whereas Excess Noise Ratio (ENR) equal to 16 dB (10 square microns diode) and 19 dB (20 square microns diode) are observed at 40 GHz, for a current density of 0.1 mA per square micron. For the first time the ENR is studied as a function of the physical device temperature, showing a slight decrease of -0.008 dB/K as the temperature increases from 298 to 358 K. An accurate modeling of the noise source is finally provided through a small-signal equivalent circuit that can be easily implemented into Computer Aided Design (CAD) tools. This contains some modifications with respect to the original Gliden and Hines model. The obtained results enable the employment of p-i-n avalanche noise diodes for the automatic characterization of integrated circuits in the production environment, as well as for the calibration of millimeter-wave receivers and radiometers during their operational life.

This letter deals with microwave noise diodes in avalanche regime. Starting from the model proposed by Hines and Gliden in 1966, the asymptotic excess noise ratio (ENR) expression is derived for ω → 0. The developed theory is then validated against ENR measurements of three noise diodes already published in the literature. The agreement between theory and measurements is good and the obtained formula also predicts the 1/I ₀ behavior of the ENR at low frequencies. This study is relevant because it simplifies the experimental determination of the average time between two ionizations (the Hines τ _x model parameter) by means of low-frequency noise measurements only.