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.123:
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
465 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
(1)
, 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 250 kHz
Butterworth IIR 0.1 dB passband (ωp)
(2)
DC to 0.7 * ωc (for ωc > 100 kHz, DC to 0.6 * ωc, due to analog anti
-
alias filter bandwidth)
Butterworth IIR filter stopband attenuation (δs)
75 dB
Butterworth IIR filter roll
-
off
48 dB/octave
100
Magnitude [%]
102.33
101.74
101.16
100.58
99.43
98.86
98.29
97.72
100
102.33
101.74
101.16
100.58
99.43
98.86
98.29
97.72
Magnitude [%]
Frequency [kHz]
Magnitude
[dB
]
1000
100
10
1
0.1
± 10 V: Butterworth 200 kHz
Passband flatness
0.2
Specification line
Specification line
0.1
0
0.05
0.15
-0.1
-0.15
-0.05
-0.2
Frequency [kHz]
Magnitude
[dB
]
± 10 V: Butterworth 200 kHz Overview
Frequency [kHz]
Magnitude
[dB
]
1000
100
10
1
0.1
± 2 V: Butterworth 200 kHz
Passband flatness
0.2
0.1
0
0.05
0.15
-0.1
-0.15
-0.05
-0.2
Frequency [kHz]
Magnitude
[dB
]
± 2 V: Butterworth 200 kHz Overview
-130
-110
-90
-70
-50
-30
-10
10
0.1
1
10
100
1000
10000
-130
-110
-90
-70
-50
-30
-10
10
0.1
1
10
100
1000
10000
Figure A.124:
Representative Butterworth IIR examples
(1)
Division by 4 not possible for the 2 MS/s sample rate
(2)
Measured using a Fluke 5700A calibrator, DC normalized
GEN3i
I3763-3.1 en HBM: public
531
