This filter is an 8-order Butterworth low-pass filter with 1V/V gain. The cut-off frequency is designed to be 4kHz with 0.5dB allowable pass band ripple.
Figure 1. 8-order Low-pass Chebyshev
Filter
As shown in the figure below, the curve is based on measured data of the filter on the board.
Figure 2. Gain vs. Frequency Curve for the
8-order Low-pass Filter
