Differentially driven symmetric microstrip inductors

A differentially excited symmetric inductor that enhances inductor quality (Q) factor on silicon RFICs is presented. Compared with an equivalent single-ended configuration, experimental data demonstrate that the differential inductor offers a 50% greater Q factor and a broader range of operating frequencies. Predictions from full-wave simulations and a physics-based SPICE-compatible model are validated by experimental measurements on an inductor fabricated in a triple-level metal silicon technology. Application of the symmetric inductor to a cross-coupled oscillator improves output voltage swing and phase noise by 75% and 1.8 dB, respectively (for a given power consumption), while chip area is reduced by 35% compared to conventional inductor equivalents.