A Regenerative Frequency Comb

Abstract--We describe a regenerative frequency comb generator (RCG) used to synthesize a signal coherent with the input signal with a fractional multiplication of m/n, where the frequency of n is proportional to 1/τ, where τ is the loop delay, and m is a positive integer less than n. We describe the RCG and compare its performance with traditional regenerative dividers, digital dividers and multipliers. Preliminary data for a divide by ten whose residual noise we measured at 100 MHz suggest superior performance to low noise digital dividers, with a SSB noise of-145 dBc/Hz at 100 Hz and 1/f characteristic. While we have not attained the broadband performance of the regenerative dividers and conjugate regenerative dividers studied in the past, we have attained-162 dBc/Hz at 100 kHz offset and expect to be able to improve the overall noise further by applying techniques investigated in the aforementioned devices. I