A highly efficient Doherty feedforward linear power amplifier for W-CDMA base-station applications

This paper presents a RF high-power Doherty amplifier for improving the efficiency of a 30-W feedforward linear amplifier used in wide-band code-division multiple-access (W-CDMA) base-station applications. A high-power Doherty amplifier using a single push-pull LDMOS field-effect transistor is proposed as the main amplifier of a feedforward linear amplifier. The peaking amplifier's compensation line and gate bias effects are analyzed at the 6-dB backoff point. From the experimental results of a forward-link one-carrier W-CDMA, a 2.2% power-added efficiency improvement at an adjacent channel leakage power ratio linearity of -60 dBc is achieved in comparison to a conventional feedforward class-AB amplifier.

[1]  Peter B. Kenington,et al.  High-Linearity RF Amplifier Design , 2000 .

[2]  George B. Norris,et al.  High efficiency CDMA RF power amplifier using dynamic envelope tracking technique , 2000, 2000 IEEE MTT-S International Microwave Symposium Digest (Cat. No.00CH37017).

[3]  George B. Norris,et al.  800 MHz power amplifier using envelope following technique , 1999, RAWCON 99. 1999 IEEE Radio and Wireless Conference (Cat. No.99EX292).

[4]  F. Raab,et al.  Power amplifiers and transmitters for RF and microwave , 2002 .

[5]  P. Asbeck,et al.  An extended Doherty amplifier with high efficiency over a wide power range , 2001, 2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No.01CH37157).

[6]  Y. Suzuki,et al.  Highly efficient feed-forward amplifier using a Class-F Doherty amplifier , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[7]  F. Raab.  Intermodulation distortion in Kahn-technique transmitters , 1996 .

[8]  Frederick Raab,et al.  Efficiency of Doherty RF Power-Amplifier Systems , 1987, IEEE Transactions on Broadcasting.

[9]  Jong-Heon Kim,et al.  RF high power Doherty amplifier for improving the efficiency of a Feedforward linear amplifier , 2004, 2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535).

[10]  W. H. Doherty.  A New High Efficiency Power Amplifier for Modulated Waves , 1936 .

[11]  Jaehyok Yi,et al.  Optimum design for linearity and efficiency of a microwave doherty amplifier using a new load matching technique , 2001 .

[12]  Bumjae Shin,et al.  A fully matched N-way Doherty amplifier with optimized linearity , 2003 .

[13]  Robert H. Caverly,et al.  HF, VHF, and UHF systems and technology , 2002 .

[14]  D. Upton,et al.  The microwave Doherty amplifier , 1994, 1994 IEEE MTT-S International Microwave Symposium Digest (Cat. No.94CH3389-4).