Butterworth IIR Filter (Digital Anti
-
Alias)
Passband
Stopband
Magnitude [dB]
δp: Passband ripple
δs: Stopband attenuation
ωp:
ωc:
Passband frequency
Corner frequency
Stopband frequency
ωs:
ωp
ωs
Frequency [kHz]
ωc
1 + δp
1 - δp
-3 dB
δs
Figure A.198:
Digital Butterworth IIR Filter
When Butterworth IIR filter is selected, this is always a combination of an analog Butterworth anti
-
alias filter and a digital Butterworth IIR filter.
Analog anti
-
alias filter bandwidth
460 kHz
±
25 kHz (
-
3 dB)
Analog anti
-
alias filter characteristic
7
-
pole Butterworth, extended passband response
Butterworth IIR filter characteristic
8
-
pole Butterworth style IIR
Butterworth IIR filter user selection
Auto tracking for sample rate divided by: 4, 10, 20, 40
The user selects a division factor from the current sample rate; software then adjusts the
filter when the sample rate is changed.
Butterworth IIR filter bandwidth (ωc)
User selectable from 1 Hz to 50 kHz
Butterworth IIR 0.1 dB passband (ωp)
(1)
DC to 35 kHz @ ωc = 50 kHz
(1)
Butterworth IIR filter stopband attenuation (δs)
75 dB
Butterworth IIR filter roll
-
off
48 dB/octave
Frequency [kHz]
Magnitude
[dB
]
100
10
1
100
10
1
0.1
4 V: Butterworth 50 kHz
Passband flatness
0.2
0.1
0
0.05
0.15
-0.1
-0.15
-0.05
-0.2
Frequency [kHz]
Magnitude
[dB
]
4 V: Butterworth 50 kHz Overview
2 V: Butterworth 50 kHz Overview
-130
-150
-110
-90
-70
-50
-30
-10
-130
-150
-110
-90
-70
-50
-30
-10
10
0.1
1
10
100
1000
10000
Frequency [kHz]
Magnitude
[dB
]
0.1
2 V: Butterworth 50 kHz
Passband flatness
0.2
0.1
0
0.05
0.15
-0.1
-0.15
-0.05
-0.2
Frequency [kHz]
Magnitude
[dB
]
10
0.1
1
10
100
1000
10000
Figure A.199:
Representative Butterworth IIR examples
(1)
Measured using a Fluke 5700A calibrator, DC normalized
GEN3i
I3763-3.1 en HBM: public
623
