An RF instantaneous-hop frequency synthesizer based on a zero-initial-phase-error multi-modulus divider

Abstract

In this paper, we propose an instantaneous-hop frequency synthesizer based on a zero-initial-phase-error multi-modulus divider that breaks the fundamental tradeoff between hopping time, spectral purity and frequency resolution. In the proposed synthesizer, initial frequency error and phase error at the instant of hop are virtually eliminated through frequency presetting in the high-resolution voltage-controlled oscillator (VCO) and the proposed zero-initial-phase-error divider. This eliminates the acquisition process and enables “instantaneous hops” to within a frequency error that is only limited by the resolution of digital control. An IC prototype is implemented and fabricated in a standard 65 nm CMOS technology. The implemented frequency synthesizer operates over 4-5.84 GHz with three discrete divider ratios (80,88,96) and achieves instantaneous hops to within an average of 3.64 MHz of the desired output frequency. The prototype dissipates 16.8 mW from 1.2 V power supply.