A 19DBM 5.8GHzz PA demonstrator with a novel low ron high FT RF LDMOS

Abstract

In this paper, we introduce an isolated RF LDMOS NFET is for RF Power Amplifier (PA) and power management applications. The RF LDMOS NFET has demonstrated a drain-source turn-on resistance (R ds,on ) of 1.45ohm-mm, a cutoff frequency (Ft) greater than 40GHz and a drain-source breakdown down voltage (BV) in excess of 9V. For PA designs, the isolation layer is floating to reduce the parasitic and achieve high PAE/nonlinearity performance. RF power amplifier cores were fabricated and measured at 2.4GHz and 5.8GHz to demonstrate the RF LDMOS performance in PAs. Under CW loadpull and 3.3V supply, 18dB and 12dB gains (Gt) are achieved at 2.4GHz and 5.8GHz respectively, with 1dB compression point power density at 22dBm/mm gate width, and PAE > 63%, maximum PAE > 70%. Due to good model to hardware Pout correlation in a 5.8GHz PA cell, a fully matched PA last stage with the load-pull fundamental and harmonic impedances showed a less than 4° AM-PM phase distortion, meeting the 802.11n spectral mask requirement with 20MHz 64QAM modulated signal at 19dBm Pout.