## 7 Experimental Results  
The features of the proposed mixed-mode universal filter configuration in Figure 3 were also verified by laboratory experiments using a commercially available IC LT1228 from Linear Technology [59]. Figure 16 shows the PCB realized for measurement purposes. The supply voltage used was \(\pm\)5 V. The experimental setup of the proposed mixed-mode universal filter utilizing the PCB board in Figure 16 is also shown in Figure 17. In CM and TIM measurements, an additional AD844 and a conversion resistor \(R_{C}\) were employed to perform the voltage-to-current conversion (V-to-I), where \(R_{C}\) = 1 k\(\Omega\). On the other hand, to obtain CM and TAM filter results, two AD844s and a resistor \(R_{C}\) were employed as a current-to-voltage converter (I-to-V). The passive and active components were selected as \(R_{1}\) = \(R_{2}\) = 1 k\(\Omega\), \(C_{1}\) = \(C_{2}\) = 100 pF, and \(g_{m1}\) = \(g_{m2}\) = 1 mA/V (\(I_{B1}\) = \(I_{B2}\) = 100 \(\mu\)A, where \(g_{mi}\) = 10 \(I_{Bj}\)). As a consequence, the theoretical filter parameters for this design were \(f_{o}\) = 1.59 MHz and \(Q\) = 1. Figure 18 shows the experimental measurements in the time domain of the input and output responses in VM operation, for a 50 mV (peak) sinusoidal  
Figure 14: Monte Carlo statistical analysis results for LP, BP, and HP responses in VM.  
Figure 15: Histogram of \(f_{o}\) distribution of the BP filter in VM.  
input voltage (\(v_{in}\)) at 1.59 MHz. The corresponding spectral analyses of the \(v_{out}\) were also measured, and the results are provided in Figure 19. The measured results indicate that the THD figures for the LP, BP, HP, BS, and AP output responses were found to be 1.23%, 2.05%, 1.78%, 0.87%, and 2.04%, respectively. Hence, they have no significant distortion that can be observed in our frequency range of interest. The experimental results of Figure 19 also show that the spurious-free dynamic range (SFDR) for the cases of LP, BP, HP, BS, and AP were determined to be 40.70 dBc, 34.60 dBc, 38.07 dBc, 44.82 dBc, and 34.66 dBc, respectively.  
Furthermore, the ideal and experimental results of the frequency-domain responses obtained from the VM, CM, TAM, and TIM filters are given in Figures 20-23, respectively. The results of Figures 20-23 show that a good agreement between experimental measurements and theoretical predictions can be observed, as desired. Additionally, the experimental THD variations of the BP output in all modes of operation are plotted for various input signal amplitudes at \(f=1.59\) MHz, as given in Figure 24.  
Figure 16: PCB of Figure 3 used for experimental verification.  
Figure 17: Experimental setup for measuring the CM, TAM, and TIM filter results.  
Figure 18: Measured time-domain waveforms of the proposed VM filter: (**a**) LP; (**b**) BP; (**c**) HP; (**d**) BS; (**e**) AP.  
Figure 19: Measured frequency spectrum of \(v_{out}\) of the proposed VM filter: (**a**) LP; (**b**) BP; (**c**) HP; (**d**) BS; (**e**) AP.  
Figure 20: Ideal (dashed line) and measured (solid line) frequency responses for VM: (**a**) LP, BP and HP; (**b**) BS; (**c**) AP.  
Figure 23: Ideal (dashed line) and measured (solid line) frequency responses for TIM.  
Figure 21: Ideal (dashed line) and measured (solid line) frequency responses for CM.