An oscillating circuit having improved noise degeneration includes an
oscillator and a noise degeneration circuit. The oscillator is adapted to
provide a differential oscillating signal between first and second output
terminals, and includes first and second transistors in communication
with the first and second output terminals. The noise degeneration
circuit includes cross-coupled capacitors and cross-coupled third and
fourth transistors operated in a linear region. The noise degeneration
circuit reduces the low frequency gm of the first and second transistors
to lower the effect of flicker noise. At relatively high frequencies, the
capacitors provide a virtual AC ground to the source terminals of the
first and second transistors. The noise degeneration circuit receives a
voltage signal from a biasing circuit adapted to track variations in
electrical characteristics of the third and fourth transistors.