Low-Cost Microwave Noise Source Exploiting a BJT with Junctions in Avalanche Regime

Abstract

In this work the feasibility of a low-cost microwave noise source compatible with commercial BiCMOS technologies is discussed. The proposed circuit exploits the avalanche noise generated by the base-emitter junction of a Bipolar Junction Transistor (BJT) in reverse breakdown. The collector terminal is not used and thus it is left open. The feasibility study is carried out exploiting the BFP640 device, a packaged BJT realized with a $f_{T}= 70$ GHz process. A breakdown current of about 3 mA is obtained by reverse biasing the base-emitter junction at 4.5 V. In these conditions the Excess Noise Ratio (ENR) of the source is greater than 20 dB from 0.5 to 4.5 GHz.