哈工大模拟coms第13章_nonlinearity_mismatch.ppt

Design of Analog Integrated Circuits Nonlinearity and Mismatch outline 1. Nonlinearity 2. Mismatch 1. Nonlinearity 1.1 General Consideration 1.1 General Consideration 1.1 General Consideration (cont.) 1.2 Nonlinearity of Differential Circuits 1.3 Effect of Negative Feedback on Nonlinearity 1.3 Effect of Negative Feedback on Nonlinearity 1.4 Capacitor Nonlinearity 1.5 Linearization Techniques 1.5 Linearization Techniques (cont.) 1.5 Linearization Techniques (cont.) 2. Mismatch 2.1 Introduction 2.2 Effect of device mismatch 2.2 Effect of device mismatch (cont.) 2.2 Effect of device mismatch (cont.) 2.2 Effect of device mismatch (cont.) 2.3 Offset Cancellation Techniques 2.3 Offset Cancellation Techniques (cont.) 2.3 Offset Cancellation Techniques (cont.) 2.3 Offset Cancellation Techniques (cont.) Summary 1. Nonlinearity 非线性概念及度量 线性化技术 负反馈 工作在线性区的差动对 后校正 2. Mismatch 大尺寸器件具有小的失配 失调消除技术 输入/输出失调存储 辅助放大级消除失调 根号下的算式中后两项通常远远小于1，进行展开。 * * 提纲 非线性 The nonlinear behavior of a circuit can also be viewed as variation of the slope and hence the small-signal gain with the input level. For small x，y(t)=α1x(t) 非线性 非线性 Method 1: to specify the maximum deviation of characteristic from an ideal one, and normalize the result ΔV to the maximum output swing. Method 2: by applying a sinusoid at input and measuring the harmonic content of the output. Summing the power of all of the harmonics (except that of the fundamental) and normalizing the result to the power of the fundamental. Such a metric is called the “total harmonic distortion” (THD) Quantification of linear For 3rd nonlinearity 非线性 Differential circuits exhibit an “odd-symmetric” input/output characteristic: f(-x)=-f(x) A differential circuit driven by a differential signal produces no even harmonic →↑linearity 非线性 Negative Feedback can improve linearity of circuits Considering a simple “ mildly nonlinear” system, y≈?1x+ ?2x2 Applying a sinusoidal input x(t)=Vmcosωt a b y(t) 非线性 ?2 b是微小量 Compared with that without feedback, 非线性 Li