A novel design of a 1.8 GHz input odd ratio frequency divider

A technique for building an odd ratio fixed frequency divider for a 1.8 GHz maximum input frequency is presented. The concept is based on a D flip-flop with a delay line that controls the divide integer in a feedback configuration. A divide-by-3 design example is presented in detail. The measured results show good agreement with predicted values. The divider is shown to be very stable over frequency, power and temperature variations. It is very small, produces extremely low-level spurious frequencies, has moderate residual phase noise, and is easily manufactured