Digital Signal Processing Reference
In-Depth Information
Finally, we generate the transfer function from (2.14)-(2.18). The coefficient
values determined by WFilter are shown in Figure 2.6.
2
(
.
4019
)
H
B
(
S
)
=
,
4
2
2
(
S
+
2
.
1878
⋅
S
+
1
.
4019
)
⋅
(
S
+
0
.
90620
⋅
S
+
1
.
4019
)
Figure 2.5
Pole locations for fourth-order Butterworth normalized filter.
Butterworth 4th-Order Normalized Lowpass
Selectivity: Lowpass
Approximation: Butterworth
Implementation: Analog
Passband gain (dB): -1.0
Stopband gain (dB): -18.0
Passband freq (Hz): 0.1591549431
Stopband freq (Hz): 0.3183098862
Filter Length/Order: 04
Overall Filter Gain: 1.00000000000E+00
Numerator Coefficients
QD [S^2 + S + 1 ]
== =========================================
01 0.0 0.00000000000E+00 1.40186544588E+00
02 0.0 0.00000000000E+00 1.40186544588E+00
Denominator Coefficients
QD [S^2 + S + 1 ]
== =========================================
01 1.0 9.06197420862E-01 1.40186544588E+00
02 1.0 2.18775410363E+00 1.40186544588E+00
Figure 2.6
Butterworth normalized fourth-order coefficients from WFilter.
