A Single Inductor Multiple Output DC-DC Buck Converter for Envelope Tracking Applications
Arnab Dey
IIT Kharagpur, India
Instrumentation & Signal Processing, 2013-15
Advisor : Prof. Santanu Kapat
Publication on this work :
V. I. Kumar, A. Dey and S. Kapat, "Single-Inductor Multi-Capacitor Buck Converter for High Peak-to-Average Power Envelope Tracking", in Proceedings of IEEE Applied Power Electronics Conference and Exposition (APEC), 2018, pp. 3083 - 3088.
Year : 2018
Place : San Antonio, TX, USA
Aim :
Peak power level is increasing with technology
Therefore power amplifiers need high power supplies to retain the information carried by the peaks
But as peaks stay for a very short time, FIXED high supply voltage will cause power wastage
Power wastage is reduced if power supply tracks the required power envelope
Therefore, the goal was to develop a novel DC-DC buck converter which can accommodate sharp peaks while keeping the efficiency high.
Topology :
Multiple output capacitors(C1, C2,...,Cn) are kept pre-charged at predefined voltage levels
Capacitors are switched as per tracking envelope voltage levels
As the capacitors are pre-charged unlike conventional DC-DC buck converter, output voltage rise time is very less. Therefore, it can track very sharp peaks also.
Hardware Prototype :
Designed on 4-layer PCB
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3.3 uH inductor
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20 uF output capacitors
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4 output levels
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Closed loop control on Xilinx Virtex-5 FPGA
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Customizable output voltage levels
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Experimental efficiency : 92.86% at 15W average power output
Top layer
Bottom layer
Experimental Results :
40 kHz ; Time scale : 10 µs/div
20 kHz ; Time scale : 10 µs/div
Ch 1: Reference Envelope (500 mV/div)
Ch 2: Output Voltage (2 V/div)
Ch 3: Inductor Current (2 A/div & 5 A/div respectively)