Analysis and Design of a 195.6 dBc/Hz Peak FoM P-N Class-B Oscillator With Transformer-Based Tail Filtering Marco Garampazzi, Student Member , IEEE, Paulo M. Mendes , Senior Member , IEEE,N i c o l aC o d e g a, Member , IEEE

Abstract

A complementary p-n class-B oscillator with two mag- netically coupled second h armonic tail resonators i sp r e s e n t e da n d compared to an N-only reference one. An in depth analysis of phase noise, based on direct derivation of the Impulse Sensitivity Func- tion (ISF), provides design insights on the optim ization of the tail resonators. In principle the complementary p-n oscillator has the same optimum Figure of Merit (FoM) of the N-only at half the voltage swing. At a supply voltage of 1.5 V , the m aximum allowed oscillation amplitude of the N-onl y is constrained, by reliability considerations, to be smaller than the value that corresponds to the optimum FoM even when 1.8 V thick oxidet r a n s i s t o r sa r eu s e d . For an oscillation amplitude that ensures reliable operation and the same tank, the p-n oscillator achieves a FoM 2 to 3 dB better than the N, only depending on the safety mar gin taken in the design. After frequency division by 2, the p-n oscillator has a measured phase noise that ranges from 150.8 to 151.5 dBc/Hz at 10 MHz offset from the carrier when the f requency of oscillation is varied from 7.35 to 8.4 GHz. With a power consumption of 6.3 mW, a peak FoM of 195.6 dBc/Hz is achieved.