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A Switched Capacitor Voltage Converter with Exponentially Sized Capacitor Banks for Wide Load Range
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- Authors
- Syed Asmat Ali Shah, Saad Arslan, Jae-Jin Lee, HyungWon Kim
- Issue Date
- 2020-10
- Citation
- IEEE Transactions on Circuits and Systems II : Express Briefs, v.67, no.10, pp.2049-2053
- ISSN
- 1549-7747
- Publisher
- IEEE
- Language
- English
- Type
- Journal Article
- Project Code
- 19ZB1200, Development of Core Technologies for Implantable Active Devices, Lee Jeong Ik
- Abstract
- Modern Internet-of-Things (IoT) applications need voltage converters to efficiently supply power with a small active period at various load conditions. The energy losses in such voltage converters during transitions between sleep-Active can be significant, especially when the converters deviate from their optimum load conditions. The proposed Switched Capacitor (SC) converter, fully integrated on chip, incorporates Split-Capacitor Charging (SCC) and Energy Recycling (ER) techniques to minimize the energy losses during the transitions. The converter consists of multiple capacitor banks and their size increases in a binary exponential fashion. It employs an LDO to support a wide range of output voltage levels and reduce output voltage ripple during energy recycling and Continuous phase. In addition, we introduce an efficient test circuit structure using an on-chip digital controller and reconfigurable load circuit. This test structure can eliminate the unwanted parasitic values and varying delays, which are commonly incurred in the conventional test structures of on-chip voltage converters with off-chip loads and external control signal generation. We implemented the proposed voltage converter with a complete on-chip test structure using a 0.13 \mu {\mathrm{ m}} CMOS process. Measurement results demonstrate a maximum efficiency of 86.83 % for a load current of 11\mu \text{A}. It also achieved an improvement of 64.44 % in energy efficiency over conventional voltage converters for a short active period.
- KSP Keywords
- Active period, CMOS Process, Capacitor bank, Capacitor charging, Conventional test, Digital Controller, Energy Efficiency, Energy recycling, External control, Fully integrated, Internet of thing(IoT)