Analysis and measurements of EM and substrate coupling effects in common RF integrated circuits

An investigation of coupling between inductors and resonators fabricated in Si substrates is presented and the effects on RF systems and components is discussed. EM simulators (e.g., Agilent Momentum) provide accurate near field analysis of coupling in lossy and complex silicon substrates. Measurements verify theory and a novel experimental technique to measure inductor and resonator coupling makes use of injection-lockable bipolar oscillators. The experiment is fast, accurate, and unique in that no matching, probe de-embedding, or calibration is necessary as the ratio of two on-chip signals is measured to yield the results. As an example, accounting for inductor coupling in a 4.7 GHz LNA reduces the amplifier´s gain from 22 dB to 18 dB.