Design of 900 MHz High Gain SiGe Power Amplifier with Linearity Improved Bias Circuit

A 900 MHz three-stage SiGe power amplifier (PA) with high power gain is presented in this paper. Volterra Series is applied to analyze nonlinearity sources of SiGe HBT device model clearly. Meanwhile, the influence of operating current to IMD3 is discussed. Then a β-helper current mirror bias circuit is applied to improve linearity, since the β-helper current mirror bias circuit can offer stable base biasing voltage. Meanwhile, it can also work as predistortion circuit when biasing voltages of three bias circuits are fine-tuned, by this way, the power gain and operating current of PA are optimized for best linearity. The three power stages which fabricated by 0.18 μm SiGe technology are bonded to the printed circuit board (PCB) to obtain impedances by Load-Pull system, then matching networks are done for best linearity with discrete passive components on PCB. The final measured three-stage PA exhibits 21.1 dBm of output power at 1 dB compression point (OP1dB) with power added efficiency (PAE) of 20.6% and 33 dB power gain under 3.3 V power supply voltage.





References:
[1] Eric Kerherve, Nejdat Demirel, et al. A broad and 4.5–15.5-GHz SiGe power amplifier with 25.5-dBm peak saturated output power and 28.7% maximum PAE (J). IEEE Transactions on Microwave Theory and Techniques, 2015.63(5): 1621-1632.
[2] Yan Li, Jerry Lopez, et al. Circuits and system design of RF polar transmitters using envelope-tracking and SiGe power amplifiers for mobile WiMAX (J). IEEE Transactions on Circuits and Systems I: Regular Papers. 2011.58(5):893-901.
[3] Guofu Niu, Qingqing Liang, Jhon D.Cressler, et al. RF linearity characteristics of SiGe HBTs (J). IEEE transactions on microwave theory and techniques 2001, 49(9): 1558-1565.
[4] Keng Leong F, Meyer R G. High-frequency nonlinearity analysis of common-emitter and differential-pair transconductance stages (J). IEEE Journal of Solid-State Circuits, 1998, 33(4): 548-555
[5] Keng Leong F High-Frequency Analysis of Linearity Improvement Technique of Common-Emitter Transconductance Stage Using a Low-Frequency-Trap Network (J). IEEE Journal of Solid-State Circuits, 2000, 35(8): 1249-1252.
[6] Joe Valliarampath, Saurabh Sinha. Linearity improvement analysis for power amplifier at mm-wave frequencies (J).Microwave and Optical Technology Letters, 2014, 56(3):743-748.
[7] Joe T. Valliarampath, Saurabh Sinha. Designing Linear PAs at Millimeter-Wave Frequencies Using Volterra Series Analysis (J). Canadian Journal of Electrical and Computer Engineering, 2015, 38(3):232-237.
[8] R. Wu, J. Lopez, Y. Li, and D. Lie, "A SiGe bipolar-mosfet cascode power amplifier with improved linearity for low-power broadband wireless applications," in Power Amplifiers for Wireless and Radio Applications (PAWR), 2013 IEEE Topical Conference on, Jan 2013, pp. 22-24.
[9] M. P. van der Heijden, H. C. de Graaff, and L. C. N. de Vreede, “A novel frequency-independent third-order intermodulation distortion cancellation technique for BJT amplifiers,” IEEE J. Solid-State Circuits, vol. 37, no. 9, pp. 1175–1183, Sep. 2002.
[10] Allen Katz, John Wood, Daniel Chokola. The Evolution of PA Linearization: From Classic Feedforward and Feedback through Analog and Digital Predistortion (J). IEEE Microwave Magazine.2016, 17(2):32—40.
[11] A. K. Mrunal, M. Shirasgaonkar, and R. Patrikar, “Highly linear and efficient AlGaAs/GaAs HBT power amplifier with integrated linearizer,” in Proc. IEEE Asia-Pacific Conf. Circuit Syst., 2006, pp. 1442–1445.
[12] H. H. Liao, H. Jiang, P. Shanjani, J. King, and A. Behzad, “A fully integrated 2*2 power amplifier for dual band MIMO 802.11n WLAN application using SiGe HBT technology,” IEEE J. Solid-State Circuits, vol. 44, no. 5, pp. 1361–1371, May 2009.
[13] B. Sahu and G. A. Rincon-Mora, “A high efficiency WCDMA RF power amplifier with adaptive, dual-mode buck–boost supply and bias current control,” IEEE Trans. Microw. Theory Tech., vol. 17, no. 3, pp. 238–240, Mar. 2007.
[14] P. Wambacq and W. Sansen, Distortion Analysis of Analog Integrated Circuits. Norwell, MA: Kluwer, 1998.