TITLE:
Switchable PLL Frequency Synthesizer andHot Carrier Effects
AUTHORS:
Yang Liu, Ashok Srivastava, Yao Xu
KEYWORDS:
CMOS Phase-Locked Loop, Voltage-Controlled Oscillator, Hot Carrier Effects, Jitter, Phase Noise
JOURNAL NAME:
Circuits and Systems,
Vol.2 No.1,
January
27,
2011
ABSTRACT: In this paper, a new strategy of switchable CMOS phase-locked loop frequency synthesizer is proposed to increase its tuning range. The switchable PLL which integrates two phase-locked loops with different tuning frequencies are designed and fabricated in 0.5 µm n-well CMOS process. Cadence/Spectre simulations show that the frequency range of the switchable phased-locked loop is between 320 MHz to 1.15 GHz. The experimental results show that the RMS jitter of the phase-locked loop changes from 26 ps to 123 ps as output frequency varies. For 700 MHz carrier frequency, the phase noise of the phase-locked loop reaches as low as ?81 dBc/Hz at 10 kHz offset frequency and ?104 dBc/Hz at 1 MHz offset frequency. A device degradation model due to hot carrier effects has been used to analyze the jitter and phase noise performance in an open loop voltage-controlled oscillator. The oscillation frequency of the voltage-controlled oscillator decreases by approximately 100 to 200 MHz versus the bias voltage and the RMS jitter increases by 40 ps under different phase-locked loop output frequencies after 4 hours of stress time.