Fully-isolated silicon RF LDMOS for high-efficiency mobile power conversion and RF amplification

Abstract

In this paper a fully isolated bulk Si RF LDMOS device platform is reported which has been optimized for highly efficient mobile power conversion and RF power amplification. The self-aligned RF LDMOS NFET achieves a specific on-resistance R ds, on of 0.94 ohm-mm2, a breakdown voltage >9V, an R sp ∗Q gg product of 8.3 mohm nC, and a cutoff frequency F t > 43 GHz. Complementary PFET RF LDMOS exhibit an R ds, on of 3.6 ohm-mm2 with a cutoff frequency F t > 16GHz. Integrated DC-DC SMPS fabricated with these RF LDMOS have a 2.3x area reduction over conventional 5V CMOS and a gate driver efficiency increase of at least 75%. RF LDMOS NFET power amplifier cores (RF PA) under CW load pull and 3.3V supply voltage exhibit gains (Gt) of 18dB and 12dB at 2.4GHz and 5.8GHz, respectively, with a 1dB compression power density of 22dBm/mm of gate width and a maximum PAE > 70%. RF LDMOS power cells meet the 802.11n spectral mask requirement for a 20MHz 64 QAM modulated signal with P out = 19dBm. These DC and RF results are the best reported for integrated Si LDMOS device structures, enabling the next generation of highly efficient miniaturized mobile power converters and new RF integration paradigms for mobile front-end modules.