Title :
A high-performance CMOS charge-pump for phase-locked loops
Author :
Zhou, Jianzheng ; Wang, Zhigong
Author_Institution :
Inst. of RF- & OE-ICs, Southeast Univ., Nanjing
Abstract :
In order to improve the performance of the existing CMOS charge pumps (CPs), a systematical analysis of the existing CMOS CPs is presented. The nonideal effects such as mismatches, switch errors in CMOS CPs are quantitatively or qualitatively analyzed. Based on the circuit architecture, both classification and comparison are made. An improved CMOS single-ended CP is designed in SMIC 0.18-mum CMOS technology with 1.8-V supply voltage. In the CP, the switches are located at the source of the current mirror, and these switches are implemented using transmission gates driven by a couple of complementary clock signals. In addition, a large bypass capacitor is added to the CP. These circuits are used to make the CP avoid the switch errors. On the other hand, the charging current I UP and the discharging current I DN are both derived from the same supply-independent reference current source, and a high-gain folded-cascode operational amplifier is used to make the CP evade the sourcing/sinking current mismatch caused by the channel-length modulation effect of the current mirrors. The proposed CP only occupies an active area of 100 mum x 150 mu m. Post-simulation results reveal that the proposed CP has a wide output range, from 0.25 V to 1.62 V, and near perfect current matching characteristic. The current matching precision is better than 0.0105%.
Keywords :
CMOS analogue integrated circuits; capacitors; current mirrors; operational amplifiers; phase locked loops; CMOS charge-pump; bypass capacitor; channel-length modulation; clock signal; current mirror; operational amplifier; phase-locked loops; size 0.18 mum; transmission gates; voltage 0.25 V to 1.62 V; voltage 1.8 V; CMOS technology; Charge pumps; Clocks; Coupling circuits; Mirrors; Performance analysis; Phase locked loops; Switched capacitor circuits; Switches; Voltage;
Conference_Titel :
Microwave and Millimeter Wave Technology, 2008. ICMMT 2008. International Conference on
Conference_Location :
Nanjing
Print_ISBN :
978-1-4244-1879-4
Electronic_ISBN :
978-1-4244-1880-0
DOI :
10.1109/ICMMT.2008.4540531