TY - JOUR
T1 - Wideband Hybrid Envelope Tracking Modulator with Hysteretic-Controlled Three-Level Switching Converter and Slew-Rate Enhanced Linear Amplifier
AU - Mahmoudidaryan, Parisa
AU - Mandal, Debashis
AU - Bakkaloglu, Bertan
AU - Kiaei, Sayfe
N1 - Funding Information:
Manuscript received May 2, 2019; revised July 12, 2019 and August 18, 2019; accepted August 29, 2019. Date of publication October 9, 2019; date of current version November 22, 2019. This article was approved by Guest Editor Bernhard Wicht. This work was supported in part by National Science Foundation Connection One Center, Arizona State University, AZ, USA, and in part by Qualcomm Inc., San Diego, CA, USA. (Corresponding author: Parisa Mahmoudidaryan.) P. Mahmoudidaryan was with the School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ 85287 USA. She is now with Qualcomm Inc., San Diego, CA 92121 USA (e-mail: pmahmoud@asu.edu).
Publisher Copyright:
© 2019 IEEE.
PY - 2019/12
Y1 - 2019/12
N2 - A wideband hybrid Envelope tracking (ET) modulator utilizing a hysteretic-controlled three-level switching converter (3L-SWC) and a slew-rate enhanced linear amplifier (LA) are presented. In addition to smaller ripple and lower losses of 3L-SWCs, employing the proposed hysteresis control loop results in a higher speed loop and wider bandwidth converter, enabling over 80 MHz of switching frequency. A concurrent sensor circuit monitors and regulates the flying capacitor voltage VCF and eliminates the conventionally required calibration loop to control it. The hysteretic-controlled 3L-SWC provides a high percentage of power amplifier (PA) supply load current with lower ripple, reducing the LA high-frequency current and ripple cancellation current, improving the overall system efficiency. A slew-rate enhancement (SRE) circuit is employed in the LA, resulting in slew rate of over 307 V/μs and bandwidth of over 275 MHz for the LA. The SRE circuit provides a parallel auxiliary current path directly to the gate of the class-AB output stage transistors, speeding-up the charging or discharging of output without modifying the operating point of the remaining LA, while maintaining the quiescent current of the class-AB stage. The supply modulator is fabricated in a 65-nm CMOS process. The measurement results show the tracking of long-term evolution (LTE)-40-MHz envelope with 93% peak efficiency at 1-W output power, while the SRE is disabled. Enabling the SRE, it can track LTE-80-MHz envelope with peak efficiency of 91%.
AB - A wideband hybrid Envelope tracking (ET) modulator utilizing a hysteretic-controlled three-level switching converter (3L-SWC) and a slew-rate enhanced linear amplifier (LA) are presented. In addition to smaller ripple and lower losses of 3L-SWCs, employing the proposed hysteresis control loop results in a higher speed loop and wider bandwidth converter, enabling over 80 MHz of switching frequency. A concurrent sensor circuit monitors and regulates the flying capacitor voltage VCF and eliminates the conventionally required calibration loop to control it. The hysteretic-controlled 3L-SWC provides a high percentage of power amplifier (PA) supply load current with lower ripple, reducing the LA high-frequency current and ripple cancellation current, improving the overall system efficiency. A slew-rate enhancement (SRE) circuit is employed in the LA, resulting in slew rate of over 307 V/μs and bandwidth of over 275 MHz for the LA. The SRE circuit provides a parallel auxiliary current path directly to the gate of the class-AB output stage transistors, speeding-up the charging or discharging of output without modifying the operating point of the remaining LA, while maintaining the quiescent current of the class-AB stage. The supply modulator is fabricated in a 65-nm CMOS process. The measurement results show the tracking of long-term evolution (LTE)-40-MHz envelope with 93% peak efficiency at 1-W output power, while the SRE is disabled. Enabling the SRE, it can track LTE-80-MHz envelope with peak efficiency of 91%.
KW - Envelope tracking (ET)
KW - LTE-advanced
KW - hybrid
KW - hysteresis control
KW - long-term evolution (LTE)
KW - power amplifier (PA)
KW - slew-rate enhancement (SRE)
KW - supply modulator
KW - three-level switching converter (3L-SWC)
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U2 - 10.1109/JSSC.2019.2941014
DO - 10.1109/JSSC.2019.2941014
M3 - Article
AN - SCOPUS:85075622763
SN - 0018-9200
VL - 54
SP - 3336
EP - 3347
JO - IEEE Journal of Solid-State Circuits
JF - IEEE Journal of Solid-State Circuits
IS - 12
M1 - 8863502
ER -