FIR (Fc @
-
0.1 dB) Filter (Digital Anti
-
Alias)
ωp = ωc ωs
Passband
Stopband
δp : Passband ripple
δs : Stopband attenuation
ωp
ωc
ωs
: Passband frequency
: Corner frequency
: Stopband frequency
Frequency [kHz]
Magnitude [dB]
δs
1 + δp
1 - δp
Figure A.74:
Digital FIR (Fc @
-
0.1 dB) filter
When FIR (Fc @
-
0.1 dB) filter is selected, this is always a combination of an analog Butterworth anti
-
alias filter and a digital FIR filter
Analog anti
-
alias filter
Characteristic
7
-
pole Butterworth, extended passband response
Bandwidth
300 kHz
±
20 kHz (
-
3 dB) All Ranges < 200 mV
350 kHz
±
20 kHz (
-
3 dB) All Ranges ≥ 200 mV
Digital FIR (Fc @
-
0.1 dB) filter
Characteristic
12
-
pole FIR; FIR is a purely digital characteristic. Its closest analog resemblance is to an
Elliptic filter. However, FIR has both ringing on the signal before the step input is started
and ringing after the step input is complete.
User selection
Auto tracking for sample rate divided by: 4, 10, 20, 40
User selects divide factor, software then adjusts filter when sample rate is changed
Bandwidth (ωc)
User selectable from 0.031 Hz to 50 kHz
0.1 dB passband flatness (ωp)
(1)
DC to ≈ωc
For all Ranges < 200 mV, ωp is limited to 10 kHz due to the anti
-
alias filter
Stopband attenuation (δs)
60 dB
Roll
-
off
72 dB/Octave
Frequency [kHz]
1000
100
10
1
0.1
Frequency [kHz]
Magnitude [dB]
-150
-130
-110
-90
-70
-50
-30
-10
10
Magnitude [dB]
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
10000
1000
100
10
1
0.1
±20 mV
FIR (Fc @-0.1 dB) 50 kHz Overview
±20 mV
FIR (Fc @-0.1 dB) 50 kHz Passband flatness
0
Magnitude [%]
2.33
1.74
1.15
0.57
-0.57
-1.14
-1.71
-2.28
Frequency [kHz]
1000
100
10
1
0.1
Frequency [kHz]
Magnitude
[dB]
-150
-130
-110
-90
-70
-50
-30
-10
10
Magnitude
[dB]
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
10000
1000
100
10
1
0.1
±1 V
FIR (Fc @-0.1 dB) 50 kHz Overview
±1 V
FIR (Fc @-0.1 dB) 50 kHz Passband flatness
0
Magnitude
[%]
2.33
1.74
1.15
0.57
-0.57
-1.14
-1.71
-2.28
Figure A.75:
Representative FIR examples
(1)
Measured using a Fluke 5700 calibrator, DC normalized
GEN3i
472
I3763-3.1 en HBM: public
