EOS and ESD damage affects device functionality and RF performance. Therefore, it is important to make thorough investigations concerning ESD protection, especially for the MIM capacitors, in order to guarantee the required ESD robustness.

Figure 5 shows a complete ESD simulation setup consisting of the implemented ESD model (HBM, MM or CDM), the parasitics of the measurement setup, and the device under test (DUT). The investigations are focused on HBM, with corresponding values for R_M = 1500 Ω, C_M = 100 pF, and L_M = 0 nH ⁵.

In order to investigate the ESD protection of the filter sub-circuits (L_D || C_D), a simple ESD model was developed. First of all, parasitic board elements are neglected so that only the parameter for HBM and the filter sub-circuit are considered. For this case, a linear differential equation of third order with the general solution is obtained.

x(t) = (U_CM, U_CD, I_LD)^T is the state vector corresponding to the state variables of the electrical network, where A represents the system matrix.

With the initial conditions for current and voltages, the vector x₀ is given by (U₀, 0, 0)^T.

Figure 6 shows the simulation results of equation 1 for the voltage drop at the capacitor C_D (1 pF) for different L values ranging from 1 nH to 30 nH. Improved ESD protection for the capacitor C_D can be achieved with smaller values of the inductance L_D. Additionally, the inductor L_D of the LC resonator determines the pole of the transfer function and is, therefore, important for the overall filter performance.

To investigate the complete ESD setup, the board parasitics must be determined and included in the circuit simulator. The parameter extraction for the board parasitics is carried out in the following manner: First, the measurement equipment is characterized by current discharge for different terminations (0 Ω and 500 Ω) for the DUT, with which the board elements can be determined. Figure 7 shows simulated and measured results for a shorted device under test.

Transient simulations for the PCN/PCS bandpass filter with internal active and passive elements were carried out with the circuit simulator (ADS) from Agilent. Figure 8 shows the simulation results of the voltage drop for several MIM capacitors and reveals the endangered element for ESD damage.

The performance of a monolithic integrated PCN/PCS RF bandpass filter with mode conversion, integrated dc power supply and ESD protection was discussed. Good RF filter performance in combination with ESD protection was achieved. The figure of merits of the RF filter are the insertion loss within the passband of -2.5 dB, the third harmonic suppression of -45 dB, the common mode suppression of -40 dB, and the ESD robustness of more than 3 kV.

The authors thank W. Zimmermann for his helpful discussions.

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Harald Böhm is a staff engineer at Infineon Technologies AG in Munich, Germany. He holds a Dr.-Ing. degree from Technical University of Munich.

Herbert Kebinger is an RF design engineer at Infineon Technologies AG in Munich, Germany, where he has been involved in application and design engineering in the areas of RF power modules and semiconductors. He is a graduate of the FH München Electrical Engineering.

Reinhard Losehand is an innovation manager in the High-Performance Active and Passive Integration group at Infineon Technologies AG in Munich, Germany. He holds a Dipl. Phys. from Technische Hochschule Munich.

Heinrich Heiss is responsible for technical marketing of silicon discrete components at Infineon Technologies AG in Munich, Germany. He holds Master and Ph.D. degrees from Technical University of Munich.

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