The proposed 2.5-GHz-band impulse transmitter technology realizes frequency-stable impulse generation against PVT variation and superior energy-per-bit operation, and it can be powered directly from a − 19.5-dBm-sensitivity RF energy harvesting circuit without any regulators that are generally essential to power RF circuits. The transmitter occupies 0.38 mm 2 in a 65nm CMOS technology. The maximum frequency difference among measured output return-loss peak of 9 chips with 3 different process corners under 0.5 V supply is about 50 MHz without any frequency calibration. Our prototype achieves 1 Mb/s signal transmission under 2.3 µW power consumption from 0.5 V supply thanks to pulse-level duty cycling operation of maximally digital architecture.Index Terms -Impulse ultra-wideband radio, Ultra low power RF, RF energy harvesting I. INTRODUCTIONThe impulse ultra-wideband (I-UWB) RFID technique has been leading short-range wireless communication technology toward internet-of-things application due to its abilities of high throughput, low power consumption and so on. While previous works have realized complicating I-UWB transceivers [1], [2], one of the next significant challenges for the short-range tag technology is how to minimize the cost for expanding its application especially toward low-end and large-volume markets.This paper proposes 2.5-GHz-band impulse transmitter (TX) technology which can contribute to save a tag cost in term of power supply and form factor. Features of our approaches are (1) frequency-stable impulse generation technique, and (2) pulse-level duty cycling with suppressed leakage by maximally digital architecture. The proposed technique can generate an impulse signal with stable RF carrier-frequency against PVT variation, which enables to remove supply-voltage conditioning circuits such as regulators and to be powered by a proposed RF energy harvesting circuit (RF-EH) directly. This paper also addresses ideas to achieve both ultra-low power consumption and superior energy per bit concurrently.

No abstract

To improve the performance of light electric vehicles (LEVs), we propose a current sharing control system for series-parallel changeover, whose hybrid energy storage system (HESS) comprises an electric double-layer capacitor (EDLC) bank and a main battery. In the proposed system, the series or parallel connection between the EDLC bank and the main battery is decided depending on the bank voltage for managing the energy stored in the HESS. Moreover, we propose a simple output current control method for the parallel connection of the EDLC bank. This method allows for the ratio of output current in both storage components to be controlled by introducing a share command parameter. Experimental results from field tests demonstrate the parallel operation with adjustable current sharing control. Finally, we discuss the combination of series-parallel operations to provide power assistance for LEVs.

No abstract

An 8 channel output switching driver has been implemented for integrated micro-electro-mechanical systems (MEMS) device control using the 0.18 µm CMOS process technology. The driver can output 20 V switching signals for 1 nF capacitive loads with a 3.3 V power supply. The switching time is less than 100 µs. To obtain a high output voltage that exceeds the transistors’ and capacitors’ breakdown voltages, a new charge pump and a discharge circuit, using optimal transistor-well-biasing techniques for triple-well-structured n-MOS transistors, were investigated, and the circuit parameters were also optimized to obtain high-speed switching.