900 MHZ radio-frequency identification rectifier with optimization and reusing of electro-static discharges protections in 180 nm digital CMOS technology

Sensitivity and electro-static discharges (ESD) protection level are crucial parameters for any Ultra High-Frequency (UHF) power rectifier–harvester designed for radio-frequency identification (RFID) devices. While sensitivity limits the reading range of the interrogator-to-tag communication link, the requirement for an adequate protection against ESD is enforced in commercial devices connected to a printed antenna. Both resistive and capacitive parasitics of the protection circuits severely affect RF performance of the device. In the paper, a rectifier for UHF RFID embedding an ESD protection for 2 kV human-body discharge model (HBM) level is proposed. The target of a low added parasitic capacitance is achieved by adapting the protection circuit to the RFID rectifier and reusing the ESD clamp for additional functions being mandatory in a UHF RFID front end. The layout of the ESD clamp has been optimized for minimum parasitic resistance without sacrificing the protection level. Two UHF harvesters were implemented in a 180 nm digital complementary metal-oxide semiconductor (CMOS) technology, featuring a minimum sensitivity of −15.5 dBm with an ESD protection level of 2 kV HBM.