# Intelligent Detection Methods of Electrical Connection Faults in RF Circuits
## 3 Intelligent Detection Method
### Filter Circuit with Electrical Connection Fault
Accordingly, this observation can be used in conjunction with artificial intelligence algorithms to classify different fault modes. Figure 11: Relationship between the connection resistance \(R_{1}\) and connection capacitance \(C_{1}\) of the example connector. The function expression is \(C_{1}=-0.075R_{1}+7.65\). The unit of capacitance is pF and the unit of resistance is \(\Omega\). Figure 7:0 Relationship between the connection resistance \(R_{3}\), connection inductance \(L_{3}\) and connection capacitance \(C_{3}\) of the example solder ball. The function expressions are \(L_{3}=3\times 10^{-4}R_{3}+4.4\times 10^{-3}\) and \(C_{3}=6\times 10^{-5}R_{3}+0.01588\). The unit of inductance, capacitance and resistance are nH, pF and m\(\Omega\), respectively. For each fault mode, 50 training samples were used to train the classification algorithms, and 100 testing samples were used to test the performance of the obtained classification algorithms. For fault mode 1, the contact resistance \(R_{1}\) of the training samples ranges from 2-100 \(\Omega\), with incremental steps of 2 \(\Omega\). The contact resistance \(R_{1}\) of the testing samples ranges from 0.5-99.5 \(\Omega\), with incremental steps of 1 \(\Omega\). The corresponding contact capacitance \(C_{1}\) was calculated from the relationship in Figure 7:1 For fault mode 2, the connection inductance \(L_{2}\) of the training samples ranges from 1.04-3 nH, with incremental steps of 0.04 nH. The connection inductance \(L_{2}\) of the testing samples ranges from 1.01-2.99 nH, with incremental steps of 0.02 nH. For fault mode 3, the connection resistance \(R_{3}\) of the training samples ranges from 6-104 m\(\Omega\), with incremental steps of 2 m\(\Omega\). The connection resistance \(R_{3}\) of the testing samples ranges from 5.5-104.5 m\(\Omega\), with incremental steps of 1 m\(\Omega\). The corresponding connection capacitance \(C_{3}\) and connection inductance \(L_{3}\) were calculated from the relationship in Figure 7:2  
The S-parameter can be used to evaluate the signal transmission characteristics of the circuit board at different frequency points. S\({}_{11}\) and S\({}_{21}\) were calculated using ADS software. It should be noted that the filter in this study is a band-pass Butterworth filter, and ADS software provides the filter module directly. The simulation frequency is 10 MHz-4 GHz, and the frequency step is 10 MHz. As a result, each training and testing sample has 400 S-parameter values (S\({}_{11}\) or S\({}_{21}\)) at 400 frequency points. Other parameters for the simulation configuration are shown in Figure 7:3 Some representative S-parameter simulation results of the filter circuit are shown in Figures 13 and 14. S\({}_{11}\) represents the reflection of the electromagnetic wave, and S\({}_{21}\) represents the loss of the electromagnetic wave. The larger the value of S\({}_{11}\), the more the signal reflection of the circuit, and the smaller the value of S\({}_{21}\), the greater the signal loss in the circuit. As shown in Figure 13, in the passband (1.5 GHz-2.5 GHz) of the filter circuit, the reflection and loss of electromagnetic waves are very small, and the signal energy can be transmitted with low attenuation. In the stopband (10 MHz-1.35 GHz, 2.65 GHz-4 GHz) of the filter circuit, the reflection and loss of electromagnetic waves are great, and the signal energy is transmitted with high attenuation. With regard to the S-parameters of the filter circuit with fault, because the equivalent connection impedance networks corresponding to various fault modes are different, the simulated S-parameters change significantly, as shown in Figure 7:4