A UHF RFID to I2C Bridge IC with Configurable Power Storage Unit for Flexible RFID Sensor Applications

Abstract

This paper presents the design of a fully passive 865MHz to 867MHz UHF RFID to $I^{2}$C Bridge IC with an integrated $I^{2}$C master for external digital sensor communications. To provide energy for external devices operation such as sensors, microcontrollers and memories, a Power Storage Unit (PSU) is directly integrated within the IC with an external capacitor as an energy storage element. Hence for communicating with external devices, the IC requires no additional power management components. Additionally, the on-chip $I^{2}$C master eliminates the need for external microcontroller, thus making the system more energy efficient and well suited for ultra-low power (ULP) sensing applications requiring battery free operation. The results show that this IC dynamically supplies an external non-volatile memory and a multi-sensor with 1.8V output voltage and is capable of handling a dynamic load current of up to 1mA required for multi-sensor readout operation. The memory and the multi-sensor are configured individually for timing and communication, while the sensor data is readout by RFID reader successfully. The chip is fabricated in a standard $0.18 \mu \mathrm{m}$ SOI CMOS technology and its achieved performance are demonstrated in this paper in combination with a high-performance commercial-of-the-shelf sensor capable of measuring air temperature, humidity, and pressure.