IEEE MTT-S 2008 International Microwave Symposium Technical Program

Session: THP2D	Interactive Forum:
Chair:	Daniela Staiculescu, Georgia Institute of Technology
Co-Chair:	Ronglin Li, Georgia Institute of Technology

THP2D-01	Characterization of Switched Mode LDMOS and GaN Power Amplifiers for Optimal Use in Polar Transmitter Architectures
1384	H. Mashad Nemati¹, C. Fager¹, U. Gustavsson³, R. Jos², H. Zirath¹, ¹Chalmers University of Technology, Gothenburg, Sweden, ²NXP Semiconductors, Nijmegen , Netherlands, ³Ericsson AB, Stockholm, Sweden
	In this paper, switch mode power amplifiers with different classes of operation and device technologies are characterized versus input power and output supply voltage. The results are used to identify optimal control schemes for use in polar transmitter architectures. Then the effects of different control schemes on the requirements for the power amplifier, and the envelope amplifier, as the main building blocks of this architecture, are investigated.

THP2D-02	A 120 Watt, Two-stage, LDMOS Power Amplifier IC at 1.8 GHz for GSM/EDGE Applications
1177	L. Zhao, G. Bigny, J. Jones, Freescale Semiconductor, Tempe, United States
	A 120 Watt LDMOS radio frequency integrated circuit (RFIC) targeting 1.8 GHz GSM, EDGE, and Evolved EDGE base station applications has been developed using state of the art design techniques and LDMOS technology. The amplifier was designed to cover the 1.8 GHz to 2 GHz GSM bands, and performs exceptionally well under both GSM and EDGE conditions. The two-stage, single-chip design exhibits 27 dB of gain and delivers 132 Watts of output power (1 dB compression; 27 Volt DC supply) with an associated PAE of 51%. Under EDGE modulation, at an average output power of 46 Watts, the EVM is less than 1.6% and the spectral re-growth is -63 dBc and -78 dBc at 400, and 600 kHz offsets, respectively. This is the highest power, 1.8 to 2 GHz, two-stage RFIC in an over-molded plastic package, reported to date.

THP2D-03	Digital Baseband Injection Techniques to Reduce Spectral Regrowth in Power Amplifier
1461	M. Xiao, P. Gardner, University of Birmingham, Birmingham, United Kingdom
	Two novel injection techniques reduce adjacent channel power ratio (ACPR) in a nonlinear power amplifier (PA). The first injects two “brick-wall” signals covering the adjacent channel bandwidths. All the injected sub-frequencies have the same amplitude but different phases. Tuning these phases, we plot the output signal to determine the appropriate sub-frequency amplitudes and phases to reduce ACPR. The second technique injects cubic products of the original signals, covering the adjacent channels. Both techniques, considered in theory and practice, can reduce spectral regrowth by nearly 30dB. The first is conceptually simple while the second is more practical for embedding into a predistorter.

THP2D-04	Wide Bandwidth Adaptive Digital Predistortion of Power Amplifiers Using Reduced Order Memory Correction
1520	R. N. Braithwaite, Powerwave Technologies, Santa Ana, United States
	Adaptive digital predistortion (DPD) with memory correction is made challenging when the observation bandwidth used to measure the output signal is narrower than the discernable intermodulation (IMD) products generated by the input signal and power amplifier nonlinearity. This paper proposes a method based on eigenvalue decompositions to reduce the order of the memory coefficient estimation. It also shows how measurements from multiple narrow bandwidth observations can be combined to increase the available rank of the estimation and improve the overall cancellation performance. Experimental results obtained using a RF test bench comprising a Doherty PA and a 20 MHz input signal demonstrate the relationship between the available order of the estimation, the number of observation bandwidths used, and the performance of the wide bandwidth IMD cancellation.

THP2D-05	Novel Approach for Static Nonlinear Behavior Identification in RF Power Amplifiers Exhibiting Memory Effects
1643	O. Hammi¹, S. Carichner², B. Vassilakis², F. M. Ghannouchi¹, ¹University of Calgary / Schulich School of Engineering, Calgary, Canada, ²Powerwave Technologies inc., Santa Ana, United States
	In this paper, an experimental approach is proposed to accurately identify, under a modulated signal drive, the memoryless nonlinearity of power amplifiers exhibiting memory effects. It is experimentally demonstrated that, when they are present, memory effects bias the extracted static nonlinearity. Accordingly, the sampling rate of the WCDMA test signal waveform is varied to reduce the signal’s bandwidth. It is shown that this approach minimizes the memory effects contribution to the amplifier’s nonlinear behavior and leads to accurate characterization of the “true” static nonlinearity. The performance of the proposed approach is then assessed through experimental memoryless digital predistortion.

If you encounter any problems, please contact