Design of highly efficient narrowband Class-E Microwave Power Amplifier with Inverter as Pre-driver

Abstract

Low Power Transmitter design requires to optimize the energy efficiencies of key building blocks including Voltage Controlled Oscillator, Mixer, and Power Amplifier (PA). Traditional Power Amplifier design for low power application use various classes of amplifiers such as Class A, Class AB, Class E to avoid output filters that degrades the output efficiency. Class-E PA is a nonlinear switching type PA which can ideally achieve 100% efficiency. Generally the output of the Power Amplifier should match with antenna's 50Ω resistance; this high efficiency has spurred many research interests on the design and analysis of Class-E PAs. The aim of the paper is to design a microwave PA which works in the narrow band range of 2.35-2.45GHz. This paper presents a new Class-E PA with a π-matching output network which produces increased efficiency. The proposed circuit consists of power amplifier stage along with the Pre-driver stage. The Pre-driver stage is an indispensable stage when we refer to the rest of power amplifier. The N-Channel Field Effect Transistor (NFET) Inverter with a serial inductor reduces the power consumption of the switching capacitance of the PA stage is used as the pre driver stage. The PA stage realised by NFET. In order to increase the efficiency of PA a parallel inductor is introduced to the conventional Class-E PA structure. The Proposed structure needs a supply voltage of 0.5 V. The structure is simulated using the Advanced Design System (ADS) simulator. The output of the simulator produces graph of current with time and voltage with time. The efficiency of the PA is also plotted using ADS. It is possible to achieve increased efficiency when the width of the transistor is reduced. The inductor introduced at the output stage also has an impact on the efficiency of the PA. The proposed PA finds applications in Bio-Telemetry, short distance communications etc.