低杂散锁相环中电荷泵的设计

Design of a Charge Pump for Low-Spur Phase Locked-Loops

采用IBM0．18μm CMOS工艺，设计了一款应用于433MHzASK接收机中低杂散锁相环的电荷泵电路。设计采用与电源无关的带隙基准偏置电流源和运算放大器，实现了电荷泵充放电电流源的精确匹配，有效抑制了传统电荷泵对锁相环锁定状态中杂散信号的影响。电路在Cadence的Spectre工具下进行仿真，结果表明：当电源电压为1．8V、参考电流为30μA、输出电压范围在0．5～1．5V时，充放电电流精确匹配，杂散小于-80dB，其性能符合接收机系统要求。

A charge-pump for low spur PLL in 433 MHz ASK receiver was designed and implemented in IBM 0. 18μm CMOS technology. An operational amplifier and a supply-independent biasing current source were used to make charging and discharging currents match. Spurs were effectively suppressed in PLL output spectrum. Results from Spectre simulation showed that the charge pump, operating at 1. 8 V with 30 μA of current, had good matching characteristics between charging and discharging currents in 0. 5-1.5 V voltage range, with spurs less than -80 dB.