Global stability analysis and stabilization of a class-E/F amplifier with a distributed active transformer

Abstract

Abstract-Power amplifiers (PAs) often exhibit instabilities giving rise to frequency divisions or spurious oscillations. The prediction of these instabilities requires a large-signal stability analysis of the circuit. In this paper, oscillations, hysteresis, and chaotic solutions, experimentally encountered in a high-efficiency class-E F odd PA with four transistors combined using a distributed active transformer, are studied through the use of stability and bifurcation analysis tools. The tools have enabled an in-depth comprehension of the different phenomena, which have been observed in simulation with good agreement with experimental results. The study of the mechanism generating the instability has led to a simplified equivalent circuit from which the optimum stabilization network has been determined. The network enables a global stabilization of the circuit for all the expected operating values of the amplifier bias voltage and input power. This has been achieved with negligible degradation of the amplifier performance in terms of drain efficiency and output power. The stable behavior obtained in simulation has been experimentally confirmed.

Three-Port Reflectionless Down-Converter for Wideband and Multichannel Receiver With Flat Gain, Enhanced EVM, and High Stability

“…To globally analyze the stability of the system, pole-zero identification is applied to the closed-loop transfer function [37], [38], [39]. The pole-zero analysis can identify the unstable region according to specific circuit topology with suitable observation nodes.…”

Analysis of frequency division in microstrip circuits by using the FDTD method

“…Traveling-wave sinusoidal wire antennas were first investigated by Rothman and Karas [1]. In their structure, a sinusoidal shaped thin wire antenna was transversely radiating.…”

“…In their structure, a sinusoidal shaped thin wire antenna was transversely radiating. They also proposed a printed circuit board (PCB) version of the antenna [1,2]. Both types of antenna were operating at S-band.…”

“…Actually, parametric oscillations are generally due to a device nonlinear capacitance exhibiting negative resistance for a certain input power. This phenomenon is often responsible for the unstable behavior of power amplifiers, frequency mixers, etc [1]. On the other hand, parametric [2,3] and regenerative [4] frequency dividers are based on the generation of a sub-harmonic oscillation from a certain value of the input power.…”