A Discrete-Amplitude Pulse Width Modulation for a High-Efficiency Linear Power Amplifier

ETRI Journal

关键词: pulse modulation;    switching mode;    Power amplifier;   

Others  :  1186046
DOI  :  10.4218/etrij.11.0110.0560

【 摘 要 】

A new discrete-amplitude pulse width modulation (DAPWM) scheme for a high-efficiency linear power amplifier is proposed. A radio frequency (RF) input signal is divided into an envelope and a phase modulated carrier. The low-frequency envelope is modulated so that it can be represented by a pulse whose area is proportional to its amplitude. The modulated pulse has at least two different pulse amplitude levels in order that the duty ratios of the pulse are kept large for small input. Then, an RF pulse train is generated by mixing the modulated envelope with the phase modulated carrier. The RF pulse train is amplified by a switching-mode power amplifier, and the original RF input signal is restored by a band pass filter. Because duty ratios of the RF pulse train are kept large in spite of a small input envelope, the DAPWM technique can reduce loss from harmonic components. Furthermore, it reduces filtering efforts required to suppress harmonic components. Simulations show that the overall efficiency of the pulsed power amplifier with DAPWM is about 60.3% for a mobile WiMax signal. This is approximately a 73% increase compared to a pulsed power amplifier with PWM.

   

【 参考文献 】

• [1]A. Dupuy et al., "Digital Pulse Width Modulated Microwave Signal Using a High Efficiency Class-E Amplifier," Asia-Pacific Microw. Conf., 2003, pp. 1809-1812.
• [2]Y.X. Wang, "An Improved Kahn Transmitter Architecture Based on Delta-Sigma Modulation," IEEE MTT-S Int. Microw. Symp. Dig., 2003, pp. 1327-1330.
• [3]Y.-S. Jeon, H.-S. Yang, and S.W. Nam, "A Novel High-Efficiency Linear Transmitter Using Injection-Locked Pulsed Oscillator," IEEE Microw. Wireless Compon. Lett., vol. 15, no. 4, Apr. 2005, pp. 214-216.
• [4]Y.-S. Jeon, H.-S. Yang, and S.W. Nam, "A Power Re-Use Technique for Improved Efficiency of the Pulsed Oscillating Amplifier," IEEE Microw. Wireless Compon. Lett., vol. 16, no. 10, Oct. 2006, pp. 567-569.
• [5]V.M.E. Antunes, V.F. Pires, and J.F.A. Silva, "Digital Multilevel Audio Power Amplifier with a MASH Sigma-Delta Modulator to Reduce Harmonic Distortion," IEEE Ind. Electron. Symp., vol. 2, 2005, pp. 525-528.
• [6]V.M.E. Antunes, V.F. Pires, and J.F.A. Silva, "Narrow Pulse Elimination PWM for Multilevel Digital Audio Power Amplifiers Using Two Cascaded H-Bridges as a Nine-Level Converter," IEEE Trans. Power Electron., vol. 22, no. 2, Mar. 2007, pp. 425-434.
• [7]A. Shirvani, D.K Su, and B.A. Wooley, "A CMOS RF Power Amplifier with Parallel Amplification for Efficient Power Control," IEEE J. Solid-State Circuits, vol. 37, no. 6, June 2002, pp. 684-693.
• [8]F.H. Raab et al., "Power Amplifiers and Transmitters for RF and Microwave," IEEE Trans. Microw. Theory Tech., vol. 50, no. 3, Mar. 2002, pp. 814-826.
• [9]J. Staudinger, "Applying Switched Gain Stage Concepts to Improve Efficiency and Linearity for Mobile CDMA Power Amplification," Microw. J., vol. 43, no. 9, Sept. 2000, pp. 152-162.
• [10]F.H. Raab, "Intermodulation Distortion in Kahn-Technique Transmitters," IEEE Trans. Microw. Theory Tech., vol. 44, no. 12, Dec. 1996, pp. 2273-2278.
• [11]F. Wang et al., "An Improved Power-Added Efficiency 19-dBm Hybrid Envelope Elimination and Restoration Power Amplifier for 802.11g WLAN Applications," IEEE Trans. Microw. Theory Tech., vol. 54, no. 12, Dec. 2006, pp. 4086-4099.