Wideband PPT Class $\Phi _2$ Inverter Using Phase-Switched Impedance Modulation and Reactance Compensation

Abstract

Class <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\Phi _2}$</tex-math></inline-formula> is a suitable power amplifier (PA) topology for applications that demand low device voltage stress and simple gate driving. The push–pull with T network (PPT) version of this architecture can be advantageous over a conventional single-ended <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\Phi _2}$</tex-math></inline-formula> due to higher power capabilities through interleaving and simple closed-form design equations. The downside with this and many other switch-mode PAs is that they perform efficiently only at a single frequency with the power degrading outside the nominal point of operation. To improve upon this issue, we incorporate a phase-switched impedance modulation variable capacitor and a reactance compensation network so that the PPT <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\Phi _2}$</tex-math></inline-formula> can function across broadband. We experimentally demonstrate a 300-W PA for a 50- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\Omega }$</tex-math></inline-formula> load impedance using silicon devices. The PA achieves above 90% efficiency over approximately a 30% fractional bandwidth. The PA can also operate across broadband with light loads, where above 80% efficiency is maintained for up to five times higher load resistances. This switch-mode PA is one of the first to demonstrate such performance under load variation and across a wide bandwidth.