Deliberate Source/Load Mismatch for Linearity and Efficiency of Discrete Supply Modulated GaN PAs
Artikel i vetenskaplig tidskrift, 2024

The effect of source (gate-side) and load (drain-side) impedance match on the linearity and efficiency of an envelope-tracked power amplifier (PA) is investigated. Conventionally designed GaN PAs exhibit an increasing gain magnitude and phase with increasing drain supply voltage. When this supply voltage is dynamically modulated in discrete levels for efficiency enhancement, the changing gain distorts the output signal and degrades linearity. The dependency of the PA gain on drain supply voltage can be minimized, however, through proper selection of the source and load impedances. This is illustrated through source/load pull simulations of a 8 x 100 mu m GaN HEMT, which reveal impedances that result in low gain magnitude and phase variation. Three PA design (matching) cases are then chosen and their performances are evaluated with an ideal dynamically changing supply. For the comparison, envelope simulations with a 67.5-MHz 64-QAM signal are performed and show that dynamic supply modulation of the mismatched PA design improves linearity and efficiency over a conventional PA designed for maximum efficiency/gain. The simulation results are validated through measurements of a deliberately mismatched, 6.2-12.6-GHz, 5-W GaN MMIC PA envelope-tracked with a GaN MMIC four-level supply modulator. Compared with a static supply, the dynamic results show improvement in average efficiency and a small penalty in linearity without using DPD.

power amplifier (PA)

linearity

Envelope tracking

Impedance

Load modeling

GaN

Modulation

supply modulation

Voltage

Gain

Distortion

Linearity

Författare

Connor Nogales

University of Colorado at Boulder

Paul Flaten

University of Colorado at Boulder

Morten Olavsbraten

Norges teknisk-naturvitenskapelige universitet

Zoya Popovic

University of Colorado at Boulder

Gregor Lasser

Chalmers, Mikroteknologi och nanovetenskap, Mikrovågselektronik

IEEE Transactions on Microwave Theory and Techniques

0018-9480 (ISSN) 15579670 (eISSN)

Vol. In Press

Ämneskategorier

Telekommunikation

Beräkningsmatematik

Signalbehandling

Annan elektroteknik och elektronik

DOI

10.1109/TMTT.2024.3413531

Mer information

Senast uppdaterat

2024-08-15