Multiphase active-RC sinusoidal oscillators incorporating lowpass and allpass sections

A generic design of multiphase (m-phase) sinusoidal oscillators is presented, suitable for both odd and even output phases. The practical odd-phase oscillator described uses a lowpass section in cascade with (m $1)/2 dual-output sections having lowpass and allpass outputs with a frequency adjusted using only (m + 1)/2 grounded resistors. This is a significant improvement compared to m-phase oscillators using m cascaded lowpass or allpass sections, which require adjustment of m passive elements. It is also shown that the new oscillator design may be used as the core of even-phase oscillators having 2m outputs for m ≥ 3.