Least-Squares Phase Predistortion of a +30dBm Class-D Outphasing RF PA in 65nm CMOS
2013 (English)In: IEEE Transactions on Circuits and Systems Part 1: Regular Papers, ISSN 1549-8328, Vol. 60, no 7, 1915-1928 p.Article in journal (Refereed) Published
This paper presents a model-based phase-only predistortion method suitable for outphasing radio frequency (RF) power amplifiers (PA). The predistortion method is based on a model of the amplifier with a constant gain factor and phase rotation for each outphasing signal, and a predistorter with phase rotation only. Exploring the structure of the outphasing PA, the problem can be reformulated from a nonconvex problem into a convex least-squares problem, and the predistorter can be calculated analytically. The method has been evaluted for 5MHz Wideband Code-Division Multiple Access (WCDMA) and Long Term Evolution (LTE) uplink signals with Peak-to-Average Power Ratio (PAPR) of 3.5 dB and 6.2 dB, respectively, applied to a fully integrated Class-D outphasing RF PA in 65nm CMOS. At 1.95 GHz for a 5.5V supply voltage, the measured output power of the PA was +29.7dBm with a power-added efficiency (PAE) of 26.6 %. For the WCDMA signal with +26.0dBm of channel power, the measured Adjacent Channel Leakage Ratio (ACLR) at 5MHz and 10MHz offsets were -46.3 dBc and -55.6 dBc with predistortion, compared to -35.5 dBc and -48.1 dBc without predistortion. For the LTE signal with +23.3dBm of channel power, the measured ACLR at 5MHz offset was -43.5 dBc with predistortion, compared to -34.1 dBc without predistortion.
Place, publisher, year, edition, pages
2013. Vol. 60, no 7, 1915-1928 p.
Outphasing, amplifier, linearization, predistortion, complementary metal-oxide-semiconductor (CMOS)
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-71862DOI: 10.1109/TCSI.2012.2230507ISI: 000322331200020OAI: oai:DiVA.org:liu-71862DiVA: diva2:454672