Digital Signal Processing Systems, Basic Filtering Types, and Digital Filter Realizations - Digital Signal Processing: Fundamentals and Applications - page 187

1

p

1.0

1- p

Stopband Passband

Transition

s

0

0

p

s

FIGURE 6.17
Magnitude response of the normalized highpass filter.

The design specifications of the lowpass filter are illustrated in Figure 6.16 , where the low-
frequency components are passed through the filter while the high-frequency components are atten-
uated. As shown in Figure 6.16 , U p and U s are the passband cutoff frequency and the stopband cutoff
frequency, respectively; d p is the design parameter to specify the ripple (fluctuation) of the frequency
response in the passband; and d s specifies the ripple of the frequency response in the stopband.
The highpass filter keeps high-frequency components and rejects low-frequency components. The
magnitude frequency response for the highpass filter is demonstrated in Figure 6.17 .
The bandpass filter attenuates both low- and high-frequency components while keeping the middle-
frequency components, as shown in Figure 6.18 .
As illustrated in Figure 6.18 , U pL and U sL are the lower passband cutoff frequency and lower
stopband cutoff frequency, respectively. U pH and U sH are the upper passband cutoff frequency and
upper stopband cutoff frequency, respectively. d p is the design parameter to specify the ripple of the
frequency response in the passband, while d s

specifies the ripple of the frequency response in the

stopband.

1

p

1.0

1- p

Passband

Transitio n T r ansition

Stopband

Stopband

s

0

0

sL pL pH sH

FIGURE 6.18
Magnitude response of the normalized bandpass filter.