Investigation of Integrated Smooth Transistor’s Switching Transition Power Amplifier—2.4-GHz Realization of Class- $E_{M}$

This paper proposes a design technique for the implementation of a class-<inline-formula> <tex-math notation="LaTeX">$E_{M}$ </tex-math></inline-formula> power amplifier (PA). Class-<inline-formula> <tex-math notation="LaTeX">$E_{M}$ </tex-math></inline-formula> mode of operation has been proposed as an improved version of class-E in terms of efficiency and power gain, provided that the current fall time of switch is an appreciable portion of a period; the frequency of operation is high enough that the switching time of transistor can no longer be considered instantaneous. A novel approach for harmonic injection required for class-<inline-formula> <tex-math notation="LaTeX">$E_{M}$ </tex-math></inline-formula> operation is proposed, followed by the system of equations and the design methodology governing the proposed circuit. As a proof of concept and verification of the proposed design method, a class-<inline-formula> <tex-math notation="LaTeX">$E_{M}$ </tex-math></inline-formula> PA is designed and implemented in 0.25-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> gallium arsenide pHEMT technology. The fabricated class-<inline-formula> <tex-math notation="LaTeX">$E_{M}$ </tex-math></inline-formula> PA operates at 2.4 GHz and delivers a power of 30 dBm to the load, with the power-added efficiency of 60% and a 14-dB power gain.