Could some electronics guru please help ? I have some questions about designing high pass filters starting with a prototype filter. The designer first specifying the following four quantities:
- Pass band ripple in dB
- Stop band attenuation in dB
- Pass band edge frequency
- Stop band start frequency Using these, the filter order is calculated, followed by selecting the normalized low pass filter coefficients for that filter order. Then the coefficient values are inverted to get the coefficients for the normalized high pass filter. After that, the coefficients are frequency and impedance scaled to get the designer's filter of choice. Questions are:
- For a normalized prototype low pass filter, the cut -off frequency is 1 rad/sec. What is the cut off frequency for a normalized high pass prototype filter ? This is important, because the prototype filter by itself is pretty much useless, and it has to be frequency and impedance scaled.
Thanks in advance.