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 -33dB 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