Frequency division using an injection-locked relaxation oscillator

In this paper, the use of an injection-locked relaxation oscillator as frequency divider is proposed. An injection-lock divider can achieve high division ratios at a power consumption which is lower than that of a divide-by-two flipflop divider while operating at the same input frequency, making it suitable as a first divider in a frequency synthesizer. The theoretical performance of an injection-locked relaxation oscillator divider is discussed. From this, it is concluded that its phase-noise performance can be brought arbitrarily close to that of the signal to be divided, thus approaching the ideal frequency divider. A test design and measurement results are presented in support of this claim.