Issue link: https://iconnect007.uberflip.com/i/1391285
JULY 2021 I DESIGN007 MAGAZINE 87 impedance profile as if the capacitor on the output had a 2.7 uH ESL, which effectively removes the flat impedance plateau that the 0.91-ohm ESR created. e output impedance of the filter above 100 kHz matches the 0.91- ohm ESR of the output capacitor. At lower fre- quencies, the output impedance approaches the 0.1-ohm DC resistance of the inductor. We can also simulate the network param- eters that we may otherwise consider using to describe the filter: Z21 and S21. To do this, we need to modify the simulation circuit by specifying the ports, the termination imped- ance and add one line that links the input and output: ".net I(Rout) V2." e SPICE deck is shown in Figure 8, the result is in Figure 9. e three curves in the plot clearly illustrate the difference among them and show us why in our chosen case the voltage transfer function is a better metric. Figure 7: Input and output impedance of the full filter. Figure 8: Simulation deck for network parameters.