Theory and Implementation of a Load-Mismatch Protective Class-E PA System

Autor: Maikel Huiskamp, Jeroen Ponte, Ali Ghahremani, Anne-Johan Annema, Bram Nauta
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: IEEE transactions on circuits and systems I: regular papers, 67(2):8768004, 369-377. IEEE
ISSN: 1549-8328
DOI: 10.1109/tcsi.2019.2926468
Popis: Highly efficient switch-mode class-E power amplifiers (PAs) are sensitive to load impedance variations. For voltage standing wave ratios (VSWRs) up to 10:1, the peak switch voltage and the average switch current can increase by a factor of 1.7 and 2.5, respectively, relative to those under nominal load conditions, imposing serious reliability risks. This paper describes a technique to self-protect class-E PAs to decrease their sensitivity to load variations, relying on the tuning of the switch-tank relative-resonance frequency, implemented by an on-chip switched-capacitor bank (SCB). To validate the technique, load-pull measurements are conducted on a class-E PA implemented in a standard 65-nm CMOS technology, employing an off-chip matching network, augmented with a fully automated self-protective control loop. Under nominal conditions, the PA provides 17.8 dBm at 1.4 GHz into $50\,{\Omega }$ from a 1.2-V supply with 67% efficiency. The proposed self-protective PA can reduce its peak switch voltage below the technology- and switch design-related limit for any load with a VSWR up to 19:1 while not considerably impacting output power and efficiency, which see a maximum degradation of 1.6 dB and 6%, respectively. Furthermore, a class-E PA designed to safely handle $2.5{\times }$ the nominal average switch current can reliably operate for VSWRs up to 19:1 when protected with our technique.
Databáze: OpenAIRE