A Package-Integrated Chireix Outphasing RF Switch-Mode High-Power Amplifier

This paper describes the design and implementation of a package-integrated Chireix outphasing RF switch-mode power amplifier (PA). The optimum loading conditions, based on class E, and the Chireix compensation elements are provided to the active devices by a dedicated low-loss bondwire-based transformer power combiner that enables a very small form factor and low cost. The realized prototype achieved 70.6-W peak power with 73% peak drain efficiency at 2.3 GHz and 28 V, and up to 81% peak drain efficiency at 2.2 GHz and 20 V. When operated for maximum power at 28 V, it reached 53.5%/43.5% average drain/total efficiency for a 9.6-dB peak-to-average-power-ratio W-CDMA signal at 2.3 GHz with low ACLR1/2 levels (
${-}{\hbox{49}}$
/
${-}{\hbox{56}}$
dBc after memoryless digital predistortion). Moreover, from 2.1 to 2.4 GHz, the realized PA demonstrated more than 50% drain efficiency across
${>}{\hbox{260}}$
,
${>}{\hbox{160}}$
, and
${>}{\hbox{80}}$
MHz at 6-, 8-, and 10-dB back-off, respectively.