In this chapter, the switched-mode second-order Class-E configurations with one capacitor and one inductor and generalized load network including the finite dc-feed inductance, shunt capacitance, and series reactance are discussed and analyzed. The results of the Fourier analysis and derivation of the equations governing the operation in an idealized operation mode are presented. Based on these equations, the required voltage and current waveforms and load-network parameters are determined for both general case and particular circuits corresponding to the subharmonic Class E, parallel-circuit Class E, and even-harmonic Class-E modes. The effect of the device output bond-wire inductance on the optimum circuit parameters is demonstrated. The possibilities to realizing a Class-E approximation with transmission lines and broadband Class-E load networks are shown and discussed. The operating power gain achieved with a parallel-circuit Class-E power amplifier is evaluated and compared with the operating power gain of a conventional Class-B power amplifier. The circuit-design examples and practical implementations of the Class-E power amplifiers using a CMOS technology are given as well.