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针对传统电荷泵电荷共享引起的输出电压波动、充放电电流失配引起的电路杂波问题,设计了一种新型电荷泵。该电荷泵电路采用常数跨导轨到轨运算放大器,降低了电荷共享引起的输出电压波动;采用基于全差分放大器的负反馈结构,解决了充放电电流失配的问题。基于SMIC0.18μm CMOS工艺,利用Cadence软件完成了电路的设计与仿真。结果表明,在0.5~1.5V输出电压范围内,该电荷泵充放电电流失配小于2%;与传统电荷泵相比,该电荷泵输出电压的波动减小了1.5mV,并且采用该电荷泵的锁相环输出频谱噪声减小了10dB。
Aiming at the circuit clutter caused by the charge voltage and charge current mismatch caused by the charge sharing of the charge pump, a new type of charge pump is designed. The charge pump circuit adopts a constant transconductance rail-to-rail operational amplifier, which reduces the output voltage fluctuation caused by the charge sharing. The negative feedback structure based on the fully differential amplifier solves the problem of mismatch of the charging and discharging currents. Based on the SMIC0.18μm CMOS process, the circuit design and simulation are completed by Cadence software. The results show that the charge-discharge current mismatch of the charge pump is less than 2% in the output voltage range of 0.5 ~ 1.5V. Compared with the traditional charge pump, the fluctuation of the output voltage of the charge pump is reduced by 1.5mV. The PLL output spectral noise is reduced by 10dB.