Decreasing the Loading Effect of the TVS Diode Using a Transmission Line for RF and Microwave Applications

In this letter, a new method for decreasing the loading effect of the transient voltage suppressor (TVS) diode has been presented and its technical details are studied under the immunity standard of IEC61000-4-2. In our approach a transmission line with a specific electrical length is employed to convert the TVS diode impedance to a significant impedance at the operating frequency. As a result, the TVS diode does not have any destructive effect on the RF specifications. In addition to the simulation using ADS software, a test circuit is fabricated on a RO4003 substrate. The simulated and measured S₁₁ and S₂₁ show appropriate frequency responses. However, by applying the proposed method, a parasitic inductance in the discharge path is created that can cause significant overshoot voltages during an electrostatic discharge event. In order to handle this shortcoming, the impact of this inductance is well studied using ADS and CST software and two techniques are introduced to minimize the overshoot voltages.