Elliptic IIR Filter (Digital Anti
-
Alias)
Passband
Stopband
Frequency [kHz]
δp: Passband ripple
δs: Stopband attenuation
ωp:
ωc:
Passband frequency
Corner frequency
Stopband frequency
ωs:
ωp=ωc ωs
Magnitude [dB]
1 + δp
1 - δp
δs
Figure A.100:
Digital Elliptic IIR Filter
When Elliptic IIR filter is selected, this is always a combination of an analog Butterworth anti
-
alias filter and a digital Elliptic IIR filter.
Analog anti
-
alias filter bandwidth
465 kHz
±
25 kHz (
-
3 dB)
Analog anti
-
alias filter characteristic
7
-
pole Butterworth, extended passband response
Elliptic IIR filter characteristic
7
-
pole Elliptic style IIR
Elliptic 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
Elliptic IIR filter bandwidth (ωc)
User selectable from 1 Hz to 250 kHz
Elliptic IIR 0.1 dB passband (ωp)
(2)
DC to ωc (for ωc > 100 kHz, DC to 0.7 * ωc due to analog anti
-
alias filter bandwidth)
Elliptic IIR filter stopband attenuation (δs)
75 dB
Elliptic IIR filter roll
-
off
72 dB/octave
Magnitude
[%]
Magnitude
[%]
Frequency [kHz]
Magnitude
[dB
]
1000
100
10
1
0.1
0.2
0.1
0
0.05
0.15
-0.1
-0.15
-0.05
-0.2
Frequency [kHz]
Magnitude
[dB
]
-130
-110
-90
-70
-50
-30
-10
10
0.1
1
10
100
1000
10000
Frequency [kHz]
Magnitude
[dB
]
1000
100
10
1
0.1
0.2
0.1
0
0.05
0.15
-0.1
-0.15
-0.05
-0.2
Frequency [kHz]
Magnitude
[dB
]
-130
-110
-90
-70
-50
-30
-10
10
0.1
1
10
100
1000
10000
20 V: Elliptic 200 kHz
Passband flatness
20 V: Elliptic 200 kHz Overview
4 V: Elliptic 200 kHz Overview
4 V: Elliptic 200 kHz
Passband flatness
0
2.33
1.74
1.15
0.57
-0.57
-1.14
-1.71
-2.28
0
2.33
1.74
1.15
0.57
-0.57
-1.14
-1.71
-2.28
Figure A.101:
Representative Elliptic 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
505