# An Electronically Adjustable Floating Memcapacitor Emulator Circuit Using CDBA
## 4 Application Examples  
### Second-Order Active Low Pass Filter  
In this section, in order to observe the performance of the proposed memristor emulator in a real circuit, a second-order active low-pass filter (2 nd order active LPF) circuit is implemented as shown in Figure 13. In the circuit, instead of the standard capacitor with a value of 210 nF, a memcapacitor emulator with the same average memcapacitance value is used. The values of the other passive elements are \(R=22\) k\(\Omega\), \(R_{1}=10\) k\(\Omega\) and \(C_{1}=70\) nF and the cut-off frequency of the filter circuit is \(f_{c}=1/2\pi RC_{1}=103.34\) Hz. The effect of the memcapacitor on the circuit is analyzed and the results are compared. Figure 14 shows the voltage-frequency characteristics of the active low pass filter circuit when both the standard capacitor and the memcapacitor are used. It can be seen from Figure 14 that the low-pass filter with the memcapacitor is more effective than the standard capacitor filter in suppressing the signals. In order to verify this result, the filter circuit was implemented experimentally and it is seen in Figure 15a,b that the amplitude of the output voltage of the memcapacitor filter at a frequency of 300 Hz is 0.23 V, while the amplitude of the standard capacitor circuit is 0.32 V. This finding indicates that the memcapacitor filter circuit exhibits more efficient filtering performance than the standard capacitor filter in the stopband.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Ref.** & **Components** & **Complexity** & **Frequency Performance** & **Floating/Grounded** & **Sim/Exp.** & **Electronic Control** & **Cost** \\ \hline
**[40]** & 2 CCIL, 1 AM 1 R,3 C & Medium & 2 kHz & Grounded & Simulation Experimental & Yes & Medium \\ \hline
**[41]** & 1 VDTA,1 OTA, 1 buffer,1 R,2C & Medium & \(\sim 1.2\) MHz & Floating & Simulation Experimental & No & Medium \\ \hline
[57] & 4 CCIL,1 Opump, 1 Vractor Diode, 6 R,2 C & High & 8 kHz & Floating & Simulation Experimental & No & High \\ \hline
**[58]** & 1 FDCCIL, 1 AM, 2 MOSFETs,3 C & Medium & 1 MHz & Grounded & Simulation Only & Yes & Medium \\ \hline
**[59]** & 4 CCIL, 1 Memristor, 1 L1 R & High & Not specified & Floating & Simulation Only & No & High \\ \hline
**This study** & 1 CDBA, 2 opamp, 1 AM, 3 R,2 C & Medium & \(\sim 25\) kHz & Floating & Simulation Experimental & Yes & Medium \\ \hline \hline \end{tabular}
\end{table}
Table 6: Performance comparison of memcapacitor emulator.  
Figure 13: Second-order active LPF circuit with memcapacitor.  
A further analysis of the filter circuit involves the comparison of the reactive power value for the capacitor selected in the circuit. The reactive power values calculated using the formula \(Q=-i^{2}X_{c}\) are \(Q_{C_{M}}=-10.84\)\(\upmu\)VAR for the memcapacitor, and \(Q_{c}=-15.04\)\(\upmu\)VAR for the standard capacitor. This analysis indicates that the memcapacitor in the filter circuit consumes less reactive power than the standard capacitor and therefore has better performance in this respect. This real electrical circuit application demonstrates that the utilization of the recommended memcapacitor emulator in place of the standard capacitor yields more efficacious electrical results.