Analog Devices AD5934, Руководство пользователя, Страница: 18 / 40

AD5934
Rev. A | Page 18 of 40
Impedance Range 3 (10 kΩ to 100 kΩ)
The following conditions were used to conduct the tests shown
in Figure 24:
Output excitation voltage = 2 V p-p
Calibration impedance value, Z
CALIBRATION
= 10 kΩ
PGA gain = ×1
Supply voltage = 3.3 V
Current-to-voltage amplifier gain resistor = 10 kΩ
0.3
–0.3
10
0
532
5-
0
81
FREQUENCY (kHz)
%
I
M
P
E
DAN
CE
E
R
RO
R
35 60 100
0.2
0.1
0
–0.1
–0.2
R
FB
= 10k Ω
CALIBRATION IMPEDANCE = 10k Ω
T
A
= 25°C
50k Ω
100k Ω
Figure 24. Impedance Range 3 Typical % Impedance Error over Frequency
Impedance Range 4 (100 kΩ to 1 MΩ)
The following conditions were used to conduct the tests shown
in Figure 25:
Output excitation voltage = 2 V p-p
Calibration impedance value, Z
CALIBRATION
= 100 kΩ
PGA gain = ×1
Supply voltage = 3.3 V
Current-to-voltage amplifier gain resistor = 100 kΩ
1.0
–3.5
10
0
532
5-
0
82
FREQUENCY (kHz)
%
I
M
P
E
DAN
CE
E
R
RO
R
35 60 100
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5
–3.0
500k Ω
1M Ω
R
FB
= 100k Ω
CALIBRATION IMPEDANCE = 100k Ω
T
A
= 25°C
Figure 25. Impedance Range 4 Typical % Impedance Error over Frequency
Impedance Range 5 (1 MΩ to 2 MΩ)
The following conditions were used to conduct the tests shown
in Figure 26:
Output excitation voltage = 2 V p-p
Calibration impedance value, Z
CALIBRATION
= 100 kΩ
PGA gain = ×1
Supply voltage = 3.3 V
Current-to-voltage amplifier gain resistor = 100 kΩ
3
–9
10
0
532
5-
0
83
FREQUENCY (kHz)
%
I
M
P
E
DAN
CE
E
R
RO
R
35 60 100
1
–1
–3
–5
–7
R
FB
= 1M Ω
CALIBRATION IMPEDANCE = 1M Ω
T
A
= 25°C
1.5M Ω
2M Ω
Figure 26. Impedance Range 5 Typical % Impedance Error over Frequency
Impedance Range 6 (9 MΩ to 10 MΩ)
The following conditions were used to conduct the tests shown
in Figure 27:
Output excitation voltage = 2 V p-p
Calibration impedance value, Z
CALIBRATION
= 9 MΩ
PGA gain = ×1
Supply voltage = 3.3 V
Current-to-voltage amplifier gain resistor = 9 MΩ
4
–10
10
0
532
5-
0
84
FREQUENCY (kHz)
%
I
M
P
E
DAN
CE
E
R
RO
R
2
0
–2
–4
–6
–8
35 60 100
R
FB
= 10M Ω
CALIBRATION IMPEDANCE = 10M Ω
T
A
= 25°C
9.5M Ω
10M Ω
Figure 27. Impedance Range 6 Typical % Impedance Error over Frequency