Title
Theory and Implementation of a Load-Mismatch Protective Class-E PA System
Abstract
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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50\,{\Omega }$ </tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.5{\times }$ </tex-math></inline-formula> the nominal average switch current can reliably operate for VSWRs up to 19:1 when protected with our technique.
Year
DOI
Venue
2020
10.1109/TCSI.2019.2926468
IEEE Transactions on Circuits and Systems I: Regular Papers
Keywords
Field
DocType
Switches,Logic gates,Zero voltage switching,Electric breakdown,Degradation,Power generation
Standing wave ratio,Voltage,Standing wave,Electronic engineering,CMOS,Control system,Input impedance,Mathematics,Amplifier
Journal
Volume
Issue
ISSN
67
2
1549-8328
Citations 
PageRank 
References 
0
0.34
0
Authors
5
Name
Order
Citations
PageRank
Jeroen Ponte100.34
Ali Ghahremani211.42
Maikel Huiskamp300.34
Anne Johan Annema4243.53
Bram Nauta51770256.74