An exploration of substrate coupling at K-band between a SiGe HBT power amplifier and a SiGe HBT voltage-controlled-oscillator

This work presents a case study of circuit-to-circuit substrate coupling between a 24-GHz power amplifier (PA) and a 23-GHz voltage-controlled oscillator (VCO) implemented in a commercially-available SiGe heterojunction bipolar transistor BiCMOS technology. The concurrent operation of these two circuits on the same silicon die results in -33 dB of coupling between the PA's output and the VCO's output. Different testing configurations are considered to verify the dominant path of the coupling. These results highlight the potential challenges for silicon-based monolithic systems targeting microwave operational frequencies.