含栅源自举开关采样电路的非线性行为级模型

Modeling of Nonlinearity in Sample-and-Hold Circuits by Bootstrapped Switches

分析了采样保持电路中栅源自举开关的非线性特性,建立了行为级模型。基于MOS器件平方律模型和体效应,给出采样输出信号3次谐波失真HD3的解析表达式。通过对实际电路进行仿真验证,并与行为级模型及谐波失真解析式进行对比,谐波失真的仿真值与建模结果最大相对误差不超过6%,有效验证了行为级模型及3次谐波失真解析表达式的准确性。

A behavioral model of distortion in sample-and-hold circuits was presented, in which the distortion was mainly caused by the nonlinear on-resistance of bootstrapped switches. The expression of third harmonic distortion and on-resistance of bootstrapped switches was derived by using the MOSFET square-law model and considering the body effect. The model and expression were verified by transistor-level Cadence simulation with a large range of various circuit parameters. The result showed that the model and expression were precise with relative errors less than 6%.