# Sigma-Delta Fractional-N Frequency Synthesis - IEEE …

The paper describes a new approach to sigma-delta fractional-N frequency synthesis based on the storage of pre-generated bitstreams. By exploiting the nature of frequency hopping systems, fabrication of a hardware sigma-delta modulator can be avoided completely and instead an optimised sigma-delta sequence for each required channel is stored in fast memory. This allows reference frequencies of several hundred MHz, which provides a significant increase in the noise spreading performance of the modulator. The paper describes simulation and implementation of such a synthesiser. Both modelled and measured results are shown to demonstrate that a substantial improvement in performance is possible.

## Delta-Sigma Fractional-N Synthesizers Enable ..

### "Sigma-Delta Fractional-N Frequency Synthesis…

Abstract — In this paper, a high-resolution fractional-N RF frequency synthesizer is presented which is controlled by a fourth-order digital sigma–delta modulator.

### A Sigma-Delta Fractional-N Frequency Synthesizer Based …

Index Terms—Capacitance multiplier, CMOS, fractional-, frequency synthesizer, loop filter, phase-switching prescaler, phase-locked loop (PLL), sigma–delta ().