期刊名称：International Journal of Computer Science Issues
印刷版ISSN：1694-0784
电子版ISSN：1694-0814
出版年度：2012
卷号：9
期号：1
出版社：IJCSI Press
摘要：In CMOS CPs, which have Up and Down switches made of p-channel and n-channel respectively, generates fluctuations in the VCO due to current mismatch occurs when dumping the charge to the loop filter and subsequently a large phase noise on the PLL output. This paper presents a new CP circuit after detailed analysis of the current mismatch problem. It combines an error amplifier with reference current sources to achieve good current matching characteristics and lower phase noises. Charge sharing can be eliminated by using charge removal transistors. In addition, a low-voltage cascode current mirror and gain-boosting circuit are used to enhance current matching over process corners and increase the output impedance of the CP. Good current matching characteristic is achieved with less than 0.1% difference of the Up/Down current and 1% over all process variations. The CP output compliance voltage range of 0.1-1.8 V is achieved for 1.8-V supply voltage. The circuit was designed using 0.18um TSMC CMOS technology and simulated by Spectre tools.
关键词：Charge pump (CP); gain;boosting charge pump; Voltage Controlled Oscillator (VCO) low;voltage cascode current mirror; phase;locked loop (PLL).
