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vor 5 Jahren

8-2018

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RF & Wireless Figure 10:

RF & Wireless Figure 10: Simulation results for the SPICE model (left) and corresponding EM simulation (right) because it provides a wide spectra of simulation tools required for successful extraction. EM Simulation of Parts The SPICE model must be based on the correct physical model, which is provided in Microwave Office. The development of the SPICE model was done using decomposition or partitioning of the package model on different parts. The SOT343 package contains the partitions shown in Figure 2: Pin 1 – bond wire to chip Pin 2 – bond wire to chip Pin 3 – bond wire to chip Pin 4 – bond wire to chip These parts were simulated in separate EM simulations. Pins 1 and 3 were connected through the die pad and were included in the same EM model. Figure 3 shows the EM model for the pins. The pin contains three main parts: the part included in model compound, the transition between model part and outer lead part, and the lead connected later with the PCB. Each of these elements has its own parasitic characteristics. The sub-division enables the designer to discover dependencies that can’t be seen in the whole simulation. Each part of the pin has its own equivalent schematic. An example of the equivalent model is shown in Figure 5. The same method is used to create the SPICE model of the bond wires. The equivalent schematic of the bond wires is shown in Figure 6. Each part can be simulated in decomposition. Estimation of Interactions Interactions between the simulated parts must be also included in the model. For instance, capacitance between the pins should be included, as shown in Figure 7. Creation of Equivalent Circuit Taking into account the parasitics of the package pins and die pad and their interactions, the entire model can now be created (Figure 8). Validation of Model in Frequency and Impedance Range Quality assurance of the equivalent circuit of the package is completed by testing each of the pins and also by testing the com- 48 hf-praxis 8/2018

RF & Wireless plete model with different port impedances. Testing on this model was made on the 100 Ohm, 50 Ohm, and 10 Ohm port impedances. Testing for Pin 1 is shown in Figure 9. The differences between the SPICE model and the corresponding EM simulation are shown in the Smith charts in Figure 10. The differences between the EM and SPICE models were numerically modeled and the results of the testing on Port 1 are shown in the graphs in Figure 11. It can be seen that the differences between the models did not exceed the -50 dB threshold. The same tests were done on Ports 2, 3, and 4. Figure 11: Simulation results for the EM and SPICE models at 50 Ohms, 300 Ohms, and 10 Ohms Conclusion Product development cycles are among the most critical aspects in the development of electronic devices, as they define cost, performance, and time to market. Fast development time and the possibility of fast tuning and design reuse have become important competitive factors. From a practical perspective, this means that the performance of devices predicted in simulation software must be very close to measured performance. A high correlation between calculated performance during design time and obtained performance strongly depends on the quality of simulation algorithms, as well as the quality of the component models. This application note has described the investigation process and results of package performance for a BFP650 BJT NPN transistor package. The quality and accuracy of the simulation using NI AWR Design Environment for 3D EM simulation and parasitics extraction was verified with measured results. The quality of package model was improved and a new model was created. Problems during the verification of semiconductor devices is the result of a combination of active and passive parts in the whole device. Because EM simulation can’t predict performance of nonlinear parts, the precision depends on the quality of the nonlinear model and comparison of measurement and simulation is not possible. In this case, the correlation of EM simulators can improve predictability. In this application note, the correlation between measurement and simulation was done using packages with different combinations of bond wires. Analyst enabled the designer to model the geometry of these devices and provided results close to measurement. Special thanks to Infineon Technologies, and Andriy Gordiyenko, AG-RF-Engineering & Consulting, for his contributions to this application note. ◄ hf-praxis 8/2018 49

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