Improvement of Intermodulation Distortion Asymmetry Characteristics With Wideband Microwave Signals in High Power Amplifiers

This paper presents the improvement techniques of intermodulation-distortion asymmetries with wide carrier-spacing signals in L/S-band high power amplifiers. We proposed a novel circuit technique to directly connect LC series resonant circuits to the gate and drain electrodes of the transistor die in a package for baseband terminations with a wide frequency range. By applying this circuit technique to a 28-V operation 200-W GaAs heterojunction field-effect transistor (HJFET) amplifier, the third-order intermodulation distortion (IMD3) asymmetries were improved even if the two-tone carrier spacing (Deltaf) exceeds 100 MHz. In addition, we analyzed the IMD3 asymmetries of a Doherty amplifier through the IMD3 vector combination of the main and peak amplifiers. A newly developed 28-V operation 200-W GaAs HJFET Doherty amplifier with source and load baseband terminations also delivered flat IMD3 characteristics against the Deltaf over 50 MHz.

[1]  J.M. Nebus,et al.  Analysis of low frequency memory and influence on solid state HPA intermodulation characteristics , 2001, 2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No.01CH37157).

[2]  Jose C. Pedro,et al.  Two-tone IMD asymmetry in microwave power amplifiers , 2000, 2000 IEEE MTT-S International Microwave Symposium Digest (Cat. No.00CH37017).

[3]  A. Mediavilla,et al.  Characterizing the gate to source nonlinear capacitor role on FET IMD performance , 1998, 1998 IEEE MTT-S International Microwave Symposium Digest (Cat. No.98CH36192).

[4]  Junko Morikawa,et al.  Improved IMD Characteristics in L/S-Band GaAs FET Power Amplifiers by Lowering Drain Bias Circuit Impedance , 1999 .

[5]  I. Takenaka,et al.  A Distortion-Cancelled Doherty High-Power Amplifier Using 28-V GaAs Heterojunction FETs for W-CDMA Base Stations , 2006, IEEE Transactions on Microwave Theory and Techniques.

[6]  Bumman Kim,et al.  Optimum operation of asymmetrical-cells-based linear Doherty power Amplifiers-uneven power drive and power matching , 2005, IEEE Transactions on Microwave Theory and Techniques.

[7]  V. Aparin,et al.  Effect of out-of-band terminations on intermodulation distortion in common-emitter circuits , 1999, 1999 IEEE MTT-S International Microwave Symposium Digest (Cat. No.99CH36282).

[8]  P. Colantonio,et al.  Investigation of IMD asymmetry in microwave FETs via Volterra series , 2005, European Gallium Arsenide and Other Semiconductor Application Symposium, GAAS 2005.

[9]  Wan-Jong Kim,et al.  Digital predistortion of a Doherty amplifier with a weak memory within a connected solution , 2004, IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004.

[10]  Jose C. Pedro,et al.  Accurate simulation of GaAs MESFET's intermodulation distortion using a new drain-source current model , 1994 .

[11]  Kouji Ishikura,et al.  High Power GaAs Heterojunction FET with Dual Field-Modulating-Plates for 28 V Operated W-CDMA Base Station , 2007, IEICE Trans. Electron..

[12]  Timo Rahkonen,et al.  Measurement technique for characterizing memory effects in RF power amplifiers , 2001 .

[13]  Yoshikazu Murakami,et al.  An investigation of IM3 distortion in relation to bypass capacitor of GaAs MMIC's , 1996, IEEE 1996 Microwave and Millimeter-Wave Monolithic Circuits Symposium. Digest of Papers.

[14]  Jose C. Pedro,et al.  A comprehensive explanation of distortion sideband asymmetries , 2002 .

[15]  J.R. Gajadharsing,et al.  Analysis and design of a 200 W LDMOS based Doherty amplifier for 3 G base stations , 2004, 2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535).

[16]  Anthony E. Parker,et al.  Effect of baseband impedance on FET intermodulation , 2003 .

[17]  Timo Rahkonen,et al.  Distortion in RF power amplifiers , 2003 .

[18]  T. Ogawa,et al.  High efficiency feed-forward amplifier using RF predistortion linearizer and the modified Doherty amplifier , 2004, 2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535).