Enhanced Digital Synthesized Phase Locked Loop with High Frequency Compensation and Clock Generation

• Published in: Sensing and imaging 2020-12, Vol.21 (1), Article 43
• Main Authors: Priyanka, E. B., Thangavel, S., Pratheep, V. G.
• Format: Article
• Language: English
• Subjects: Circuits; CMOS; Decibels; Design; Electrical Engineering; Engineering; Figure of merit; Imaging; Kalman filters; Microwaves; Original Paper; Phase locked loops; Phase locked systems; Power consumption; Radiology; RF and Optical Engineering; Topology; Tuning; Voltage controlled oscillators
• ISSN: 1557-2064; 1557-2072
• DOI: 10.1007/s11220-020-00308-0

The proposed work concentrates on the integration of an 8-GHz voltage-controlled oscillator (VCO) and a frequency tripler for 24-GHz local oscillator generation. By stacking the VCO and the tripler with a current-reused topology, the power consumption of this integration can be saved. The proposed circuit with a total chip area of 0.7 mm ×0.8 mm is implemented in a 0.18 μm CMOS process. As the tuning voltage increases from 0 to 2 V, the measured frequency tuning range (FTR) of the VCO is from 7.06 to 8.33 GHz. The final resulting output frequency from the tripler ranges from 21.18 to 24.98 GHz (16.5% FTR). The core circuit totally consumes 5 mA from a 1.8-V supply voltage. The measured phase noises at the VCO and frequency tripler outputs are − 113.76 and − 105.1 dBc/Hz at 1-MHz offset frequency, respectively, when V tune is 0 V. The best evaluated figure of merit with tuning is − 187.2 dBc/Hz (decibels relative to carrier). Closed form equations allow for a performance driven design for both PLL and estimator. By using a variable sample frequency controlled by the PLL, the Kalman filter is always operated around its center frequency, which is the rated grid frequency. The new topology is compared to other published single-phase PLL designs and its operation is verified by both simulations and experiments. This integration of a VCO and a frequency tripler exhibits a high potential for the use in low-power 24-GHz phase-locked loops. The PLL designed using dual mode logic technique exhibits excellent performance even under severely distorted utility grid voltage conditions. This robustness makes it very suitable for use in systems connected to grids having an important share of non-linear loads.