Analysis of current efficiency for CMOS class-B and class-C LC oscillators working in triode region

A study of current efficiency for CMOS class-B and class-C LC oscillators working in triode region is presented in this paper. Using Fourier-transform analysis and rigorous mathematical deduction, closed form expressions describing current efficiency are derived for class-B and class-C LC oscillators. Simulation results have been run in Cadence SpectreRF using 0.13-um standard RF CMOS technology, which are in good agreements with the theoretical expressions.