A 6.6 mW 1.25–2.25 GHz low phase noise PLL frequency synthesizer based on wide tuning range Class-C VCO. (August 2017)

• Record Type: Journal Article
• Authors: Lin, Jianfu; Song, Zheng; Wei, Meng; Chi, Baoyong
• Is Part Of: Microelectronics journal. Volume 66(2017)
• Page Start: 119
• Page End: 127
• Publication Date: 2017-08
• Subjects: Class-C voltage-controlled oscillator (VCO) -- Wide tuning range -- Low phase noise -- Phase-locked loop (PLL) -- IEEE 802.11ah -- Frequency synthesizer -- CMOS; Microelectronics -- Periodicals; Microélectronique -- Périodiques; Microelectronics; Electronic journals; Journals - contents and abstracts; Periodicals; 621.3805
• DOI: 10.1016/j.mejo.2017.06.007
• Languages: English
• ISSNs: 0959-8324

Abstract

Abstract: A wide tuning range low phase noise phase-locked loop (PLL) frequency synthesizer based on Class-C voltage-controlled oscillator (VCO) for IEEE 802.11ah is presented. Feedback loop technique is adopted to provide dynamic gate bias to the core transistors of the Class-C VCO, guaranteeing robust start-up against process, voltage and temperature (PVT) variations. Automatic frequency control (AFC) algorithm with tail bias switching scheme is proposed to guarantee start-up condition and maintain optimum oscillation amplitude across the whole tuning range, avoiding the deterioration of figure-of-merit (FoM). Implemented in 65-nm CMOS, the presented frequency synthesizer prototype achieves a tuning range of 57%, from 1.25 GHz to 2.25 GHz. Drawing 5.5 mA current from a 1.2-V power supply, the prototype demonstrates −127.8 dBc/Hz phase noise at 1-MHz offset and −94.6 dBc/Hz in-band phase noise from a carrier of 1.536 GHz. With the proposed dynamic gate bias technique and AFC-assisted tail bias switching scheme, the wide tuning range Class-C VCO exhibits a peak FoM of 187.5 dBc/Hz, with only 2.5 dB variation across the whole tuning range.