A wideband fully integrated +30dBm Class-D outphasing RF PA in 65nm CMOS

This paper presents a Class-D outphasing RF Power Amplifier (PA) which can operate at a 5.5V supply and deliver +29.7dBm with 26.6% PAE at 1.95 GHz in a standard 65nm CMOS technology. The PA utilizes two on-chip transformers to combine the outputs of four Class-D stages. The Class-D stages utilize a cascode configuration, driven by an AC-coupled low-voltage driver, to allow a 5.5V supply without excessive device voltage stress. The measured 3dB bandwidth was 1.6 GHz (1.2–2.8 GHz). The PA was continuously operated for 168 hours (1 week) without any performance degradation. To evaluate the linearity of the outphasing PA, a WCDMA and an LTE signal (20 MHz, 16-QAM) were used. At +26.0 dBm channel power for the WCDMA signal, the measured ACLR at 5MHz and 10MHz offset were −35.6 dBc and −48.4 dBc, respectively. At +22.9 dBm channel power for the LTE signal, the measured ACLR at 20MHz offset was −35.9 dBc.

[1]  J.R. Long,et al.  Shielded passive devices for silicon-based monolithic microwave and millimeter-wave integrated circuits , 2006, IEEE Journal of Solid-State Circuits.

[2]  Atila Alvandpour,et al.  A +32 dBm 1.85 GHz class-D outphasing RF PA in 130nm CMOS for WCDMA/LTE , 2011, 2011 Proceedings of the ESSCIRC (ESSCIRC).

[3]  J.S. Yuan,et al.  MOS RF reliability subject to dynamic voltage stress-modeling and analysis , 2005, IEEE Transactions on Electron Devices.

[4]  John R. Long,et al.  A 58–65 GHz Neutralized CMOS Power Amplifier With PAE Above 10% at 1-V Supply , 2010, IEEE Journal of Solid-State Circuits.

[5]  M. Ruberto,et al.  A reliability-aware RF power amplifier design for CMOS radio chip integration , 2008, 2008 IEEE International Reliability Physics Symposium.

[6]  Yorgos Palaskas,et al.  A highly linear 25dBm outphasing power amplifier in 32nm CMOS for WLAN application , 2010, 2010 Proceedings of ESSCIRC.

[7]  K. Soumyanath,et al.  A 28.1dBm class-D outphasing power amplifier in 45nm LP digital CMOS , 2009, 2009 Symposium on VLSI Circuits.

[8]  J.S. Yuan,et al.  Evaluation of RF-Stress Effect on Class-E MOS Power-Amplifier Efficiency , 2008, IEEE Transactions on Electron Devices.

[9]  F. Svelto,et al.  Oxide Breakdown After RF Stress: Experimental Analysis and Effects on Power Amplifier Operation , 2006, 2006 IEEE International Reliability Physics Symposium Proceedings.

[10]  Jeffrey S. Walling,et al.  A switched-capacitor power amplifier for EER/polar transmitters , 2011, 2011 IEEE International Solid-State Circuits Conference.

[11]  Ali Hajimiri,et al.  Distributed active transformer-a new power-combining and impedance-transformation technique , 2002 .