In this chapter we continue our introduction to circuit analysis by studying periodic functions in both the time and frequency domains. Any periodic function may be represented as the sum of an infinite number of sine and cosine functions which are harmonically related. The response of the linear network to the general periodic forcing function may be obtained by superposing the partial responses

In this chapter we will develop the concept of average power as distinguished from instantaneous power. We will also be concerned with apparent power, power factor, and complex power. By the way, we discuss the maximum amount of power transfer from the source to the load

In the chapter we shall introduce the study of circuits characterized by a single energy-storage element--a capacitor or a inductor. It will be shown that the equations describing such a circuit may be put in a form involving an unknown variable and its first derivative. Such an equation is referred to as a first-order differential equation, thus we shall refer to circuits which contain only a single energy-storage element as first-order circuits

6.1二端口网络的方程与参数 6.2二端口网络的连接与等效 6.3二端口网络的网络函数与特性阻抗

第三节 有端接的双口网络 有端接情形下的双口网络， 双口网络分析与应用。 第七章：链式网络与传输线 第一节 传输线 链式网络: 传输线, 均匀无耗传输线

频谱密度、基本性质和定理、基本信号的频谱密度、频移定理、波形失真、不失真条件、因果律

§3-2 非周期信号的频谱密度  傅立叶变换与频谱密度  信号的频谱分布与带宽  基本信号的频谱密度 §3-3 频谱分析的基本定理

双端口网络的Z参量 双端口网络的Y参量、H参量、G参量、A参量 双端口网络的串联和并联

 互易双端口网络的等效网络  非互易双端口网络的等效网络 重点关注： 互易条件 等效网络

北京大学：《电路分析原理 Circuit Analysis》课程教学资源（课件讲稿）第六章 双端口网络的分析方法 §6-3 有端接的双端口网络 §6-4 双端口网络的链联 §6-5 集成差分放大器（1/2）