Abstract: A new configuration for delay cells used in voltage controlled oscillators is presented.A jitter comparison between the source-coupled differential delay cell and the proposed CMOS inverter based delay cell is given.A new method to optimize loop parameters based on low-jitter in PLL is also introduced.A low-jitter 1.25GHz Serdes is implemented in a 0.35μm standard 2P3M CMOS process.The result shows that the RJ (random jitter) RMS of 1.25GHz data rate series output is 2.3ps (0.0015UI) and RJ (1 sigma) is 0.0035UI.A phase noise measurement shows -120dBc/Hz@100kHz at 1111100000 clock-pattern data out.

Key words: Serdes, voltage controlled ring oscillator, low jitter, 串并-并串轉(zhuǎn)換