Graduate Degree Type
School of Engineering
The applied research presented in this thesis is intended to deepen the understanding of various concepts related to PCB design with respect to EMC and RF performance. The first topic addressed is embedded capacitance of a PCB. The work includes decoupling capacitors and their placement relative to the IC in a combination of three different PCB stack-ups. The evaluation is performed in the frequency domain and time domain. The next topic discussed is the EMC/ EMI filters which are essential measurements to protect a device or subsystem from EMI. The circuit's load is usually unknown. A generic filter design is built, which allows the placement of various PCB structures to evaluate filters under different load and source impedance. To convert voltage effciently, SMPS buck converters are widely used. To suppress EMI, various counter measures for differential mode, and common mode are discussed and measured with a conducted emission (CE) voltage method (V) to evaluate their performance. The designed snubber is evaluated in the time domain by measuring the ringing and the suppressed target frequency content. The results of the above four topics are utilized in a VHF auto tuner design. The results of the embedded capacitance frequency domain evaluation show that the two evaluated 6-layer designs outperform the 4-layer design. Additionally, the 6-layer design with far spaced power plane outperforms the 6-layer version 3 design with not-far spaced power plane referenced to the top signal layer. Grouped capacitors outperform the not grouped capacitors. For not grouped capacitors on a 6-layer design, the evaluation in time and frequency domain shows that the 6-layer designs are particularly enhancing higher frequency content suppression regardless if the capacitors are grouped or not. The filter evaluation showed that for a 2nd order filter the capacitor placed close to the high impedance side shows increased performance. The 3rd order structures π and T show that there is no significant performance decrease if the filter is mounted one way or another. The correlation of the measured and simulated data showed that the ideal case simulations are valid for the ideal behavior of the filter. Due to the bandwidth of a π filter, large components with lower self-resonance frequencies are favorable. In real-world applications, a π is favorable because there never is just an LC or CL structure due to bulk or decoupling capacitors. The SMPS evaluation showed that the snubber could be designed with Adamczyk's and Spence's approach. The tested EMC filter structures showed clearly that a single component shows an impact on the CE (V) measurement and can be identified by its self-resonant frequency. The filter can be designed for different target frequency ranges, and depending on the design, it will show better or worse results. The shield was added, and the measured interference dropped mainly to the ambient level. On the VHF auto tuner each evaluated topic is discussed and shows that around 50% of the used components are related to EMC. The presented work illustrates the multidisciplinary character of electromagnetic compatibility (EMC).
Häring, Dimitri, "EMC Performance Evaluation of Various PCB Designs through Simulation and Measurements" (2019). Masters Theses. 954.