Reduction of intrinsic 1/f device noise in a CMOS ring oscillator

The implications of intrinsic 1/f device noise reduction in MOS transistors due to periodic on-off switching in a CMOS ring oscillator are explored. It is shown that maximising the amplitude of oscillation helps to reduce the close-in phase noise. Measurement results, corrected for amplitude-dependent upconversion and effective bias show an improvement of 8 dB in phase noise at 1KHz frequency offset from the carrier at 4.5 dB increase in carrier power.