Low Phase Noise Phase-locked Loop Research Articles

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

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 1.25GHz to 2.25GHz. Drawing 5.5mA 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 1.536GHz. 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 2.5dB variation across the whole tuning range.

A low-chip area and low-phase noise hybrid phase-locked loop

A low-chip area and low-phase noise phase-locked loop (PLL) combining fractional-N and integer-N modes operating at 2.4 GHz band is proposed and fabricated in TSMC 0.18-μm CMOS process.The proposed PLL with a Gm-boosted Colpitts voltage-controlled oscillator improves phase noise and a hybrid design of different divider loops achieves fast lock. At 1.8 V supply voltage, the proposed PLL shows a wide tuning range from 2.14 to 2.36 GHz, corresponding to 9.7%, a phase noise of −119.3 dBc/Hz at an offset frequency of 1 MHz from the carrier frequency of 2.14 GHz, a power consumption of 17.3 mW, and an output power of −15.37 dBm. Including pads, the chip area only occupies 0.588 (0.87 × 0.67) mm2. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2295–2300, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27082

A 0.8 V low power low phase-noise PLL

A low power and low phase noise phase-locked loop (PLL) design for low voltage (0.8 V) applications is presented. The voltage controlled oscillator (VCO) operates from a 0.5 V voltage supply, while the other blocks operate from a 0.8 V supply. A differential NMOS-only topology is adopted for the oscillator, a modified precharge topology is applied in the phase-frequency detector (PFD), and a new feedback structure is utilized in the charge pump (CP) for ultra-low voltage applications. The divider adopts the extended true single phase clock DFF in order to operate in the high frequency region and save circuit area and power. In addition, several novel design techniques, such as removing the tail current source, are demonstrated to cut down the phase noise. Implemented in the SMIC 0.13 μm RF CMOS process and operated at 0.8 V supply voltage, the PLL measures a phase noise of-112.4 dBc/Hz at an offset frequency of 1 MHz from the carrier and a frequency range of 3.166-3.383 GHz. The improved PFD and the novel CP dissipate 0.39 mW power from a 0.8 V supply. The occupied chip area of the PFD and CP is 100 × 100 μm2. The chip occupies 0.63 mm2, and draws less than 6.54 mW from a 0.8 V supply.