A Low Phase Noise Class-C Oscillator With Improved Resonator and Robust Start-Up

This brief presents a new resonator for class-C oscillators which not only decreases the phase noise, but solves their inevitable start-up problem. The aforementioned resonator has two separate nodes that increasing inductance energy factor (IEF) in output node provides lower phase noise. By connecting a class-B active pair to the other node of the resonator, with larger equivalent impedance, start-up problem has been solved. By reaching the steady state, the auxiliary class-B active pair transistors will be switched off in order to achieve lower phase noise besides power consumption goals. The proposed oscillator, implemented in 130 nm standard CMOS technology, oscillates at the frequency of 3.4 GHz and its phase noise is about -136.8 dBc/Hz at 3 MHz offset. The power consumption and FoM are 9.5 mW and 188.1 dBc/Hz, respectively.