Transient safe operating area (TSOA) definition for ESD applications

The concept of Transient Safe Operating Area (TSOA) for electrostatic discharge (ESD) design is discussed in this paper. TSOA characterization is introduced to obtain ESD design targets and better synthesize protection-/core- devices actual transient over-voltage response for robust ESD performance in emerging high-voltage mixed-signal circuit applications. A first methodology based on the direct analysis of the transient response of output devices and clamps is demonstrated to achieve optimum protection of commonly sensitive high voltage output devices by either enabling self-protection or by combining the output device with a protection clamp. To extend the TSOA analysis and address the different problem of thin MOS gate oxide protection, a power-law based method is introduced to assess the TSOA and consistently provides effective input circuit protection. The TSOA is identified via fast transient measurements and ESD robustness is further evaluated in conjunction with protection devices.