How to simulate for charge pump leakage?

Can anyone please show how to simulate for charge pump leakage? And what's the typical requirement on its amplitude? Thank you so much.

Is the charge pump for PLL or power supply generator? If it is for PLL, you can implement the leakage curret by paralelling a ideal current source in the output of the charge pump. And the typical leakge current is about 10~30nA in current submicron cmos process.