Bidirectional Floating-Base BJT Esd Protected Rfid Chip

Abstract

The maximum peak-to-peak radio frequency (RF) signal antenna voltage level can be extended to reach to over 12 Vpp, −6 V to +6 V. Thus it is desirable that the electrostatic discharge (ESD) device does not turn on at the normal operating RF antenna signal voltage level. The turn-on threshold negative voltage of the ESD device of the PN diode type is around −0.5 V in the conventional radio frequency identification (RFID) chip. The asymmetric threshold voltage characteristics of the ESD device of the RFID chip makes the distortion of the RF antenna signal at the high intensity RF input field. In the proposed floating base vertical PNP ESD device, N-type doped N-WELL floating base is sandwiched between two p-type P+ emitter and P-WELL collector. Floating base BJT ESD device enhances the performance of parasitic BJT current in the ESD mode. During the negative voltage phase of RF antenna input signal, the negative voltage of RF antenna input is extended to around −10 V. This extension of RF antenna input operation voltage range makes to prevent from any distortion of RF antenna signal at the high RF input field. The measured HBM ESD protection level of the floating base BJT ESD device is over 2000 V with the P+ anode layout area of 400 µm 2 .