An ultra-low power low cost LDO for UHF RFID tag

抄録

An ultra-low power low cost LDO (low-dropout voltage regulator) for UHF RFID tag chip is presented. In order to reduce the cost, a low temperature coefficient voltage reference with only 15 KΩ resistor is proposed, this voltage reference is based on sub-threshold operation and the power consumption is minimized. A pole-zero tracking compensation circuit is used, this scheme generates an internal zero which tracks the pole produced by the load current. The design is based on UMC 0.18µm 2P5M EEPROM process, and the active area is only 0.0146 mm². The LDO has a maximum load capacity of 5 mA while outputs a 1.1 V stable voltage. The measured undershoot and overshoot are 55 mV and 60 mV respectively. With the ultra-low power voltage reference circuit, the total quiescent current is only 370 nA under a 1.2 V power supply. The proposed regulator has been used in UHF RFID tag chips successfully.