ΣΔ调制器中非线性直流增益建模
The Nonlinear DC-gain Model in ΣΔ Modulators
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摘要: 分析了运算放大器有限直流增益和非线性直流增益对ΣΔ调制器的影响, 通过双曲正切函数模拟运算放大器的输入输出特性, 由积分器的递归解法构造了一个调制器模型.该模型可用于系统级仿真来预测非线性直流增益对调制器性能的影响, 系统级仿真和电路级仿真证明此模型行之有效.Abstract: The effects of the op-amps' Nonlinear DC-gain on Delta-Sigma (ΣΔ) modulators is studied in this paper.A system-level model consists of a hyperbolic tangent model for the input/output characteristic of op amps and a recursive solution of nonlinear integrators.The proposed model can simply be used to evaluate the effect of amplifier's DC-gain nonlinearity.Simulations at different levels of abstraction indicate the accurateness of this model.