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Automatic Adjustment of Phase Locked Loop Transfer Function
Masahiro YOSHIOKA Nobuo FUJII
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2008/02/01
Online ISSN: 1745-1337
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
phase locked loop, gain adjustment, frequency adjustment, automatic calibration,
Full Text: PDF(772KB)>>
This paper presents an automatic adjustment of the transfer function of phase locked loop (PLL). The time constants and the gain factor of the transfer function are adjusted without opening the loop of PLL. The time constant adjustment is performed using a replica of the 1st order RC low pass filter and the gain factor is adjusted by detecting the open loop gain at the unity gain frequency. These adjustments are automatically carried out using a digitally controlled capacitance array and a digitally controlled charge pump. The proposed calibration can reduce the bandwidth error of 30% to 5% and the gain error of 7 dB to 1 dB.