Design of Bessel-like filter-based ESD protection I/O pad with improved eye performance

초록

This paper presents an electrostatic discharge (ESD) protected I/O pad with the improved eye-opening performance based on the Bessel-like filter. Flat group delay performance of the Bessel-like filter enables to reduce signal distortion and improve the eye-opening performance. It consists of inductors compensating for the parasitic capacitances of ESD diodes, widening the bandwidth. The designed I/O pad was fabricated in a 28 nm CMOS process. The eye opening (i.e., the product of eye height and eye width) and 3-dB bandwidth were measured to be 15.9 pV center dot sec and 22 GHz, respectively, while satisfying the OIF-CEI 28G mask limit. Measurement results demonstrate that the proposed ESD I/O pad based on the Bessel-like filter can improve the bandwidth and eye-opening performance, compared to the basic ESD I/O pad.

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