Title :
Wideband envelope amplifier for envelope-tracking operation of handset power amplifier
Author :
Jooseung Kim ; Dongsu Kim ; Yunsung Cho ; Daehyun Kang ; Sangsu Jin ; Byungjoon Park ; Kyunghoon Moon ; Hadong Jin ; Seungbeom Koo ; Bumman Kim
Author_Institution :
Dept. of Electr. Eng., Pohang Univ. of Sci. & Technol. (POSTECH), Pohang, South Korea
Abstract :
This paper presents a wideband envelope amplifier for envelope-tracking operation of handset power amplifiers. The amplifier has a combined structure composed of a linear regulator and a switching converter. A low output impedance class-AB push-pull output stage is employed to expand the bandwidth (BW) of the linear regulator. By reducing the output resistance of the source follower using dual shunt feedbacks, a nondominant pole at the gate of the output buffer is pushed to the higher frequency range. The gain BW product (GBW) of the linear regulator is improved without sacrificing the phase margin (PM) and efficiency. The designed linear regulator achieves the GBW of 129.6-MHz and PM of 73.1 °. For a 40-MHz long term evolution signal having a peak-to-average power ratio of 7.4 dB, the envelope amplifier delivers an efficiency of 73.6% at the peak power driving a 7.7Ω resistive load.
Keywords :
VHF amplifiers; radiofrequency power amplifiers; switching convertors; wideband amplifiers; GBW; dual shunt feedbacks; efficiency 73.6 percent; envelope-tracking operation; frequency 129.6 MHz; frequency 40 MHz; gain BW product; handset power amplifiers; linear regulator; low output impedance class-AB push-pull output stage; nondominant pole; phase margin; resistance 7.7 ohm; source follower; switching converter; wideband envelope amplifier; Gain; Impedance; Peak to average power ratio; Regulators; Resistance; Switching converters; Wideband;
Conference_Titel :
Microwave Conference (EuMC), 2014 44th European
Conference_Location :
Rome
DOI :
10.1109/EuMC.2014.6986695
