Analog Integrated Circuits and Signal Processing vol:x issue:x pages:1-10
Frequency pulling of an oscillator integrated in a quadrature phase-shift keying wireless transmitter degrades the performance of the wireless system. This paper analyses the behavior of an oscillator in the presence of coupling between the oscillator and a power amplifier or antenna. Symbol switching in the modulator will cause frequency shifts in the oscillator at the modulation frequency. A new architecture for a 120 GHz quadrature frequency generator with large tuning range and immunity against PAâVCO coupling is presented. Combining the output signals of two independent oscillators, the pulling effect is removed and the frequency generator can be integrated with a PA and an antenna on the same chip. This architecture also makes quadrature generation with large tuning range feasible at 120 GHz. The chip is fabricated in a 45 nm CMOS technology and shows a tuning range of 16.2 GHz (13.5 %), a phase noise of Ã112 dBc/Hz @ 10 MHz offset and a phase error of 5Â° (Volkaerts et al. in: IEEE Radio Frequency Integrated Circuits Symposium (RFIC), 2013).