Multi‐function ESD protection circuit for UHF RFID devices in CMOS technology

Abstract

The design and implementation of an electrostatic discharge protection suitable for UHF RFID devices in CMOS technology is presented. The circuit implements three fundamental functions for the RF interface: power limiting, backscatter modulation and electrostatic discharge protection. Since all functions are achieved by the same MOS device the additional shunt capacitance at the RF inputs is limited. Therefore the maximum reading distance of the RFID device is improved without sacrificing the electrostatic protection level.

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

“…The main idea was therefore to improve the ESD robustness of the protection circuit by design, thus reaching the 2 kV HBM limit with a lower clamp size and, therefore, a lower capacitance, C ESD . The circuit in Figure implements a specific ESD protection for RFID front ends, and it is based on the concept of reusing the ESD clamp for other mandatory functions .…”

“…The main idea was therefore to improve the ESD robustness of the protection circuit by design, thus reaching the 2 kV HBM limit with a lower clamp size and, therefore, a lower capacitance, C ESD . The circuit in Figure 6 implements a specific ESD protection for RFID front ends, and it is based on the concept of reusing the ESD clamp for other mandatory functions [33]. The gates of NMOS ESD clamps M EP and M EN are now driven by the rectifier output through a diode-connected NMOS device (M B ) and by an inverter gate (M A À M C ) instead to be shorted to GND as in the typical configuration in Figure 3 It is worth to be noticed that the ESD robustness of the NMOS clamp is increased by the feedback through M A and M B .…”