Bessel IIR Filter (Digital Anti
-
Alias)
δs
ωp
ωs
Passband
Stopband
δp : Passband ripple
δs: Stopband attenuation
ωp
ωc
ωs
: Passband frequency
: Corner frequency
: Stopband frequency
Frequency [kHz]
Magnitude [dB]
ωc
1 + δp
1 - δp
-3 dB
Figure A.196:
Digital Bessel IIR Filter
When Bessel IIR filter is selected, this is always a combination of an analog Bessel anti
-
alias filter and a digital Bessel IIR filter.
Analog anti
-
alias filter bandwidth
390 kHz
±
25 kHz (
-
3 dB)
Analog anti
-
alias filter characteristic
7
-
pole Bessel, optimal step response
Bessel IIR filter characteristic
8
-
pole Bessel style IIR
Bessel IIR filter user selection
Auto tracking for sample rate divided by: 10, 20, 40, 100
The user selects a division factor from the current sample rate; software then adjusts the
filter when the sample rate is changed.
Bessel IIR filter bandwidth (ωc)
User selectable from 0.4 Hz to 20 kHz
Bessel IIR 0.1 dB passband (ωp)
(1)
DC to 3.5 kHz @ ωc = 20 kHz
Bessel IIR filter stopband attenuation (δs)
75 dB
Bessel IIR filter roll
-
off
48 dB/octave
Frequency [kHz]
Magnitude
[dB
]
100
10
1
10
1
0.1
4 V: Bessel 20 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: Bessel 20 kHz Overview
2 V: Bessel 20 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]
Ma
g
ni
tud
e
[
dB
]
1000
0.1
2 V: Bessel 20 kHz
Passband flatness
0.2
0.1
0
0.05
0.15
-0.1
-0.15
-0.05
-0.2
Frequency [kHz]
Ma
g
ni
tud
e
[
dB
]
10
0.1
1
10
100
1000
10000
Figure A.197:
Representative Bessel IIR examples
(1)
Measured using a Fluke 5700A calibrator, DC normalized
GEN3i
622
I3763-3.1 en HBM: public
