Development of an ultra-low power current reference circuit for passive RFID application in 90nm CMOS technology

This research study involved the analog CMOS design of an ultra-low power current reference applicable on wireless devices, especially on passive RFID tags. Passive RFID are battery-less circuit that needs to convert incoming RF power into a DC voltage using rectifier circuit. However, the tag can be read only at very short distances, typically a few feet at most. This greatly limits the device for certain applications. From this, a low power current reference for passive RFID applications is introduced. It is important to improve the usual way of reading tags in order to attain efficiency. This research aimed to develop an ultra-low power current reference for passive RFID application that will lower the tag circuit power consumption to longer the maximum distance required by the communication between the reader and the tag. This study is planned to be implemented on the tollgate system in the Philippines. The main application of this study was the passive RFID tag to be placed on cars. By that, the paper aimed to establish a current reference that has a stable behaviour with temperature and supply variations. This is to ensure that the reference circuit will still function, even if it was placed on different areas in the Philippines.