APPLICATION NOTE
6
Now you will simulate the bandpass circuit that has the following specifications: Lower-3dB = 1 kHz, Upper-3dB =
10 kHz, 30dB minimum at 0.2 kHz and 50 kHz.
Figure 8: Frequency response of the Butterworth bandpass filter model
The Butt_HP filter symbol has a attribute FC = 1kHz and the Butt_HP filter symbol has a attribute FCH = 5kHz for
low and high cutoff frequencies, respectively. A single AC source is frequency swept over 0.2 kHz to 50 kHz
(1001 decade). The simulated frequency response of the filter is shown in Figure 8.
Band-Reject Filter Behavioral Models
The Band-Reject Filter model is based on summing outputs of the lowpass and highpass filter models. The cutoff
frequency of the lowpass circuit defines the lower -3dB point of the bandpass filter bandwidth, while the cutoff
frequency of the highpass circuit defines the upper -3dB point of the filter bandwidth.
The three band-reject filter models are:
Butt_BR (Butterworth filter)
Ch2p5_BR (0.25dB ripple Chebyshev filter)
Bessel_BR (Bessel filter)
