Summary: 684 IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, VOL. 16, NO. 12, DECEMBER 2006
A 20 dBm Linear RF Power Amplifier Using
Stacked Silicon-on-Sapphire MOSFETs
Jinho Jeong, Member, IEEE, Sataporn Pornpromlikit, Peter M. Asbeck, Fellow, IEEE, and Dylan Kelly
Abstract--In this letter, a fully integrated 20-dBm RF power
amplifier (PA) is presented using 0.25- m-gate silicon-on-sapphire
metal-oxide-semiconductor field-effect transistors (MOSFETs).
To overcome the low breakdown voltage limit of MOSFETs, a
stacked FET structure is employed, where transistors are con-
nected in series so that each output voltage swing is added in phase.
By using triple-stacked FETs, the optimum load impedance for a
20-dBm PA increases to 50
, which is nine times higher than that
of parallel FET topology for the same output power. Measurement
of a single-stage linear PA shows small-signal gain of 17.1 dB and
saturated output power of 21.0 dBm with power added efficiency
(PAE) of 44.0% at 1.88 GHz. With an IS-95 code division multiple
access modulated signal, the PA shows an average output power
of 16.3 dBm and PAE of 18.7% with adjacent channel power ratio
below 42 dBc.