Analysis and design of distributed ESD protection circuits for high-speed mixed-signal and RF ICs

Electrostatic discharge (ESD) protection devices can have an adverse effect on the performance of high-speed mixed-signal and RF circuits. This paper presents quantitative methodologies to analyze the performance degradation of these circuits due to ESD protection. A detailed S-parameter-based analysis of these high-frequency systems illustrates the utility of the distributed ESD protection scheme and the impact of the parasitics associated with the protection devices. It is shown that a four-stage distributed ESD protection can be beneficial for frequencies up to 10 GHz. In addition, two generalized design optimization methodologies incorporating coplanar waveguides are developed for the distributed structure to achieve a better impedance match over a broad frequency range (0-10 GHz). By using this optimized design, an ESD device with a parasitic capacitance of 200 fF attenuates the RF signal power by only 0.27 dB at 10 GHz. Furthermore, termination schemes are proposed to allow this analysis to be applicable to high-speed digital and mixed-signal systems.