A Study on ESD Protection Characteristic Difference Measurement of Varistors by VNA

The protection performance of an electrostatic-discharge (ESD) protection device changes when the device is implemented in a circuit at a system level. Additionally, the operating characteristics and protection performance of an ESD-protection device may differ from device to device even if the specifications of both devices are identical. Therefore, this study aims to realize an evaluation method that can express realistic differences in the ESD-protection performance of devices relying on variable resistor (Varistor). First, we evaluated the application of the proposed method to measurement of the protection characteristics of varistors using a vector network analyzer. Second, we measured and compared three types of varistors that have identical electrical specifications. We present the measured results for the frequency responses of the identical varistors in their operating and non-operating states. The results showed that our proposed method had a possibility to be applied to a realistic evaluation of varistors.