Experimental Analysis of the Coupling Mechanisms Between a 4 GHz PPA and a 5–7 GHz $LC$-VCO

The coupling of the transmitted radio-frequency (RF) signal of the power amplifier (PA) in the sensitive voltage-controlled oscillator (VCO) remains a major problem for system-on-chip (SoC) design. Coupling between these two circuits may cause malfunctioning of the system. This paper analyzes the different coupling mechanisms between a 4 GHz prepower amplifier (PPA) and a 5-7 GHz LC-VCO designed in 0.13 mum technology. Different experiments are carried out to reveal the dominant coupling mechanisms. Insight into these mechanisms leads to the proposal of proper countermeasures.