Improvements in the flicker noise reduction technique for osillator designs

This paper presents a technique in oscillator design to reduce the flicker noise of an active device. The architecture presented consists of two feedback loops, an RF loop for the oscillator operation and a low pass loop for flicker noise reduction. Flicker noise is reduced by providing a feedback path for low frequencies. To verify the concept, simulations and measurements of a voltage control oscillator at 1.57 GHz implemented with GaAs FET are presented. Simulations and measurements verify the phase noise reduction. The measurements of the VCO with low frequency feedback has shown a phase noise performance of -134 dBc/Hz at an offset of 1 MHz from the carrier frequency, whereas for the oscillator without the low frequency feedback this value was -127 dBc/Hz. The measured improvement of 7 dB in phase noise performance supports the flicker noise reduction technique in oscillators.