Design of an Ultralow power voltage regulator for RFID applications.pdf

Design of an Ultra-low power voltage regulator for RFID applications MP3a-06 Thesis researcher: Fung Sheung Wai Supervisor : Professor Philip K.T. Mok OverView Radio Frequency Identification (RFID) is a wireless communication system that commonly used in many areas, such as assess system or tracking of object. RFID mainly consist of two parts, a reader and a tag. There are two kinds of tags, which is an active one and a passive one. For the passive tag, it does not use any battery and the power is comes form the RF (radio frequency) energy transmitted from the reader. So the power in passive tag is very limited. In addition, for the passive tag to operate properly, a more regulated DC power supply is required. Thus a Low dropout voltage regulator (LDO) is always used inside the passive tag and it is a great interest to design a LDO for passive tag. Low Dropout voltage regulator is popularly used in many portable electronic, as it can provide a low noise and regulator power supply. However, a conventional LDO is not suitable for passive tag. It is because the specifications of an LDO for passive tag are very different from the conventional one (shown in table below). Thus we need to design a new LDO for passive tag. Specifications An LDO for passive A conventional LDO tag Output 250 pF 5µF capacitance Load current 0.1 µA– 25µA 0.1mA– 100mA range Quiescent current 400nA 100µA Memory Read: Load current Load current is 100mA operation is 0.5µA for 2.5ms Write: Load current is 25µA for 6ms PSRR @100kHz -20dB @1kHz