A ΣΔ based direct all-digital frequency synthesizer with 20 Mbps frequency modulation capability and 3μs startup latency

• Published in: ESSCIRC Conference 2015 - 41st European Solid-State Circuits Conference (ESSCIRC) pp. 388 - 391
• Main Authors: Thirunarayanan, Raghavasimhan, Ruffieux, David, Scolari, Nicola, Enz, Christian
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.09.2015
• Subjects: Film bulk acoustic resonators; Frequency modulation; Frequency synthesizers; Noise; Synthesizers; Time-frequency analysis
• ISBN: 1467374709; 9781467374705
• ISSN: 1930-8833; 2643-1319
• DOI: 10.1109/ESSCIRC.2015.7313909

This paper presents an all-digital, direct frequency synthesizer that can support direct modulation data rates up to 20 Mbps for deployment in multi-hop, reconfigurable wireless mesh networks. In addition, this synthesizer can start up in only 3 us which reduces the energy overhead, thus making it attractive for duty cycling. By digitally manipulating time-shifted copies of a temperature-compensated FBAR oscillator signal based on the outputs from a Sigma-Delta modulator (SDM), the synthesizer is able to generate the desired frequency over a wide range. Integrated in a 65 nm CMOS technology, a prototype of this synthesizer generates frequencies from 2.34-2.47 GHz. Being completely digital, this synthesizer occupies a very small area of just 0.035 mm2. The synthesizer consumes 3.9 mA from a 1.1 V supply while achieving a frequency resolution of 180 Hz.