Browsing by Author "Men, Guan-Yu"

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A CHARGE PUMP WITH MPPT CIRCUIT EMPLOYED IN BATTERYLESS PHOTOVOLTAIC IOT TAGS
(2016)
Men, Guan-Yu
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Cheng, Yuan-Po
;
Chao, Paul C. -P.
;
Yang, Ching-Cheng
;
Pribadi, Eka Fitrah
A dc-dc regulator is proposed to attach to the battery-less solar tag applied in the Internet of Things (IoTs) market. Two main purposes in this design is to maximize the power transfer efficiency and to provide a high voltage supply to the back-end circuit. The overall circuit consists of the cross-coupled charge pump, optimal power point tracking and timing control circuit. It is expected to boost the input voltage from 0.55-0.65V to the output of 1-1.1V at 80-100 mu W condition. Gated PFM circuit is adopted in the optimal power point tracking system to modulate the input frequency of the charge pump to match the inner resistance of the solar cell. This system has been taped-out by TSMC 0.18UM 1P6M process twice and N-fab 0.35UM process once. The experimental results of this chip show that the voltage conversion efficiency (VCE) is 97% and the power conversion efficiency (PCE) is 11.7% at 30 W input power condition. The reason of the low efficiency has been found and improved by enhancing the pumping capacitance. The efficiency of the 3rd tape-out in N-fab has been improved to 81.2% according to the simulation results.
An 80% Effeciency and Highly Adaptable PV Energy Harvest Circuitry With MPPT for IOT Devices
(2017-01-01)
Cheng, Yuan-Po
;
Chao, Paul C. -P.
;
Men, Guan-Yu
;
Yang, Ching-Cheng
;
Wang, Tong-Wen
An on-chip DC-DC converter for energy harvesting is proposed for a new battery-less solar cell tag applied to the Internet of Things (IoTs) devices. The main purpose of this design is to maximize the transfer efficiency and to stably provide a high enough supply voltage to the back-end loads. The overall circuit consists of a cross-coupled charge pump, a maximum power point tracking (MPPT) circuit, a timing control circuit and regulator. The input voltage range is from 0.45V to 3V. The output voltage can be boosted to the required level, in the range of 1V to 3.3V, with more than 60% power conversion efficiency. The throughput power is at least 500 mu W. A gated clock frequency modulation circuit is designed and adopted in the MPPT unit to lock the input resistance of the charge pump. In addition, a low-dropout (LDO) regulator circuit is used to provide a stable voltage to the load. The experimental results of chip show that the maximum power conversion efficiency (PCE) is 80% at 33 mu W input power condition.