RF Blockset 2.5

Mathematical Filters

This model compares two Chebyshev I filters of order 3 and 5 with a passband ripple of 1 dB implemented using mathematical Bandpass RF Filter blocks.

Contents

Demo Model

Filter specifications: Center frequency = 75 MHz, Lower passband edge frequency = 72 MHz and Upper passband edge frequency = 78 MHz. Based on these parameters, the bandwidth of the filter at -1 dB = (78-72) = 6 MHz.

Fig. 1 Mathematical filter demo model:

Simulation Results

The following figure shows the filter frequency responses from 70 MHz to 80 MHz. As expected, the frequency response of the 5th order filter has five ripples and the frequency response of the 3rd order filter has three ripples. Also, the roll-off of the 5th order filter is steeper than the roll-off of the 3rd order filter.

Fig. 2 Filter frequency responses: