A Transformer-Combined 31.5 dBm Outphasing Power Amplifier in 45 nm LP CMOS With Dynamic Power Control for Back-Off Power Efficiency Enhancement

A transformer-combined fully integrated outphasing class-D PA in 45 nm LP CMOS achieves 31.5 dBm peak output power at 2.4 GHz with 27% peak PAE, and supports over 86 dB of output power range. The PA employs dynamic power control (DPC) whereby sections of the PA are turned on or off dynamically according to the instantaneous signal amplitude to reduce power dissipation, especially at back-off. Dynamic on-off switching introduces transients on the power supply that can limit performance. The paper proposes and demonstrates techniques to reduce the impact of such transients. A multi-section slab inductor based transformer combiner is used to allow individual switching of unit PAs. The PA delivers 24.8 dBm average power while meeting 64-QAM WLAN requirements. PAE is 16% when using DPC, which represents a 33% efficiency enhancement compared to the DPC-disabled mode. At lower average power of 20.5 dBm, DPC enables a 140% enhancement in average efficiency, hence increasing battery life.

[1]  G. Rabjohn,et al.  A high efficiency Chireix out-phasing power amplifier for 5GHz WLAN applications , 2004, 2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535).

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

[3]  Yorgos Palaskas,et al.  A Flip-Chip-Packaged 25.3 dBm Class-D Outphasing Power Amplifier in 32 nm CMOS for WLAN Application , 2011, IEEE Journal of Solid-State Circuits.

[4]  Kyu Hwan An,et al.  A Linear Multi-Mode CMOS Power Amplifier With Discrete Resizing and Concurrent Power Combining Structure , 2011, IEEE Journal of Solid-State Circuits.

[5]  Debopriyo Chowdhury,et al.  A 90nm CMOS power amplifier for 802.16e (WiMAX) applications , 2009, 2009 IEEE Radio Frequency Integrated Circuits Symposium.

[6]  Ali Hajimiri,et al.  A Fully-Integrated Quad-Band GSM/GPRS CMOS Power Amplifier , 2008 .

[7]  L.E. Larson,et al.  CMOS Outphasing Class-D Amplifier With Chireix Combiner , 2007, IEEE Microwave and Wireless Components Letters.

[8]  H. Chireix.  High Power Outphasing Modulation , 1935, Proceedings of the Institute of Radio Engineers.

[9]  Frederick H. Raab,et al.  Efficiency of Outphasing RF Power-Amplifier Systems , 1985, IEEE Trans. Commun..

[10]  Jeffrey S. Walling,et al.  A power-combined switched-capacitor power amplifier in 90nm CMOS , 2011, 2011 IEEE Radio Frequency Integrated Circuits Symposium.

[11]  Lawrence E. Larson,et al.  A 65nm CMOS 2.4GHz 31.5dBm power amplifier with a distributed LC power-combining network and improved linearization for WLAN applications , 2010, 2010 IEEE International Solid-State Circuits Conference - (ISSCC).

[12]  Asad A. Abidi,et al.  An Outphasing Power Amplifier for a Software-Defined Radio Transmitter , 2008, 2008 IEEE International Solid-State Circuits Conference - Digest of Technical Papers.

[13]  Kyutae Lim,et al.  A 600MHz CMOS OFDM LINC transmitter with a 7 bit digital phase modulator , 2008, 2008 IEEE Radio Frequency Integrated Circuits Symposium.

[14]  A.M. Niknejad,et al.  A Fully Integrated Dual-Mode Highly Linear 2.4 GHz CMOS Power Amplifier for 4G WiMax Applications , 2009, IEEE Journal of Solid-State Circuits.

[15]  Gang Liu,et al.  Fully Integrated CMOS Power Amplifier With Efficiency Enhancement at Power Back-Off , 2008, IEEE Journal of Solid-State Circuits.

[16]  Marian Verhelst,et al.  A 2.5GHz delay-based wideband OFDM outphasing modulator in 45nm-LP CMOS , 2011, 2011 Symposium on VLSI Circuits - Digest of Technical Papers.

[17]  C.G. Sodini,et al.  A 5.8GHz, 47% efficiency, linear outphase power amplifier with fully integrated power combiner , 2006, IEEE Radio Frequency Integrated Circuits (RFIC) Symposium, 2006.

[18]  A.A. Abidi,et al.  All-Digital Outphasing Modulator for a Software-Defined Transmitter , 2009, IEEE Journal of Solid-State Circuits.

[19]  Patrick Reynaert,et al.  A fully integrated CMOS power amplifier for LTE-applications using clover shaped DAT , 2011, 2011 Proceedings of the ESSCIRC (ESSCIRC).

[20]  Lars Sundström,et al.  Investigation of a highly efficient LINC amplifier topology , 2001, IEEE 54th Vehicular Technology Conference. VTC Fall 2001. Proceedings (Cat. No.01CH37211).

[21]  Yorgos Palaskas,et al.  A 31.5dBm outphasing class-D power amplifier in 45nm CMOS with back-off efficiency enhancement by dynamic power control , 2011, 2011 Proceedings of the ESSCIRC (ESSCIRC).

[22]  Jan-Erik Mueller,et al.  A 31-dBm, high ruggedness power amplifier in 65-nm standard CMOS with high-efficiency stacked-cascode stages , 2010, 2010 IEEE Radio Frequency Integrated Circuits Symposium.

[23]  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).

[24]  Marian Verhelst,et al.  A 20dBm 2.4GHz digital outphasing transmitter for WLAN application in 32nm CMOS , 2012, 2012 IEEE International Solid-State Circuits Conference.

[25]  Sungho Lee,et al.  A CMOS Outphasing Power Amplifier With Integrated Single-Ended Chireix Combiner , 2010, IEEE Transactions on Circuits and Systems II: Express Briefs.

[26]  Ki Seok Yang,et al.  An EDGE/GSM Quad-Band CMOS Power Amplifier , 2014, IEEE Journal of Solid-State Circuits.