An Ultra-Wide Range Digitally Adaptive Control Phase Locked Loop with New 3-Phase Switched Capacitor Loop Filter

Shiro DOSHO  Naoshi YANAGISAWA  Kazuaki SOGAWA  Yuji YAMADA  Takashi MORIE  

IEICE TRANSACTIONS on Electronics   Vol.E90-C   No.6   pp.1197-1202
Publication Date: 2007/06/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e90-c.6.1197
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Related SoC Integration Technologies)
loop filter,  switched capacitor,  phase locked loop,  digital control,  adaptive control,  

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It is an innovative idea for modern PLL generation to control the bandwidth proportionally to the reference frequency. Recently, a frequency of the operating clock in microprocessors has been required to be changed frequently and widely in order to manage power consumption and throughput. A new compact switched capacitor (SC) filter which has fully flat response has been developed for adaptive biased PLLs. We have also developed a new digital control method for achieving the wider frequency range. The measured performances of the test chip were good enough for the use in the microprocessors.