锁相环中电荷泵的分析与设计

用SMIC0.18μmCMOS工艺设计了一种改进型电荷泵电路。该电路基本思想是使用电流参考支路和运放来实现充放电电流的高度匹配,改进则基于重复利用运放的考虑。传统结构为了消除电荷共享效应需要一个单位增益运放,而这一设计省去这个运放,简化了设计,同时也能够达到充放电电流的良好匹配。芯片测试结果显示,输出电压在0.4～1.4V的范围内,电荷泵充放电电流约为1.1mA,失配小于2%。

Analysis and Design of a Novel Charge Pump

A novel type of charge pump is designed with the SMIC 0.18 μm RFCMOS process. This structure uses reference branch and op-amp to realize charge and discharge current match, and the improvement is based on the reuse of op-amp. Conventional structure of this type needs one unit-gain op-amp to eliminate the charge sharing effect, which has been omitted in our design. It also has a good match between charge and discharge current. The experimental result of the chip shows when the output voltage is between 0.4～1.4V, the charge or discharge current is about 1.1 mA, and the mismatch of them is less than 2%.