Speedup of Frequency Switching Time in PLL Frequency Synthesizers Using a Target Frequency Detector

Shigeki OBOTE
Yasuaki SUMI
Kouichi SYOUBU
Yutaka FUKUI
Yoshio ITOH

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E82-A    No.3    pp.436-441
Publication Date: 1999/03/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Selected Papers from the 11th Workshop on Circuits and Systems in Karuizawa)
PLL frequency synthesizer,  target frequency detector,  fast frequency switching,  

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In this paper, we propose a speedup method of frequency switching time in the phase locked loop (PLL) frequency synthesizer using the target frequency detector (TFD). The TFD detects the time Ta for any channels where the output of the PLL frequency synthesizer reaches the target frequency for the first time. At Ta, the programmable divider, the reference divider and the phase comparator are reset, and the phase of the PLL frequency synthesizer is initialized and the phase synchronization is achieved. In the proposed method, since the ringing in the transient state does not occur, the output of the PLL frequency synthesizer converges to the target frequency at Ta and the frequency switching time is speeded up. The effectiveness of the proposed method will be confirmed by experimental results.