Loop-parameter optimization of a PLL for a low-jitter 2.5-Gb/sone-chip optical receiver IC with 1: 8 DEMUX |
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Authors: | Kishine K Ishii K Ichino H |
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Affiliation: | NTT Network Innovation Labs., Kanagawa; |
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Abstract: | A loop parameter optimization method for a phase-locked loop (PLL) used in wide area networks (WANs) is proposed as a technique for achieving good jitter characteristics. It is shown that the jitter characteristics of the PLL, especially jitter transfer and jitter generation, depend strongly on the key parameter ζωn (ζ is a damping factor and ωn is the natural angular frequency of the PLL), and that the optimization focusing on the ωn dependence of the jitter characteristics make it possible to comprehensively determine loop parameters and loop filter constants for a PLL that will fully comply with ITU-T jitter specifications. Using the optimization method with the low-jitter circuit design technique, a low-jitter and low-power 2.5-Gb/s optical receiver IC integrated with a limiting amplifier, clock and data recovery (CDR), and demultiplexer (DEMUX) is fabricated using 0.5-μm Si bipolar technology (fT = 40 GHz). The jitter characteristics of the IC meet all three types of jitter specifications given in ITU-T recommendation G.783. In particular, the measured jitter generation is 3.2 ps rms, which is lower than that of an IC integrated with only a CDR in our previous work. In addition, the pull-in range of the PLL is 50 MHz and the power consumption of the IC is only 0.68 W (limiting amplifier: 0.2 W, CDR (PLL): 0.3 W, DEMUX: 0.18 W) at a supply voltage of -3.3 V and only 0.35 W at a supply voltage of -2.5 V (without output buffers) |
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