Datasheet

AD7745/AD7746
Rev. 0| Page 9 of 28
8
–12
–250
250
05468-028
CIN LEAKAGE TO GND (nA)
CAPACITANCE ERROR (fF)
2.7V
3V
6
4
2
0
–2
–4
–6
–8
–10
–200 –150 –100 –50 0 50 100 150 200
Figure 12. Capacitance Input Error vs. Leakage Current to GND,
CIN(+) to EXC = 4 pF, CIN(−) to EXC = 0 pF,
V
DD
= 2.7 V and 3 V
8
–12
–250 250
05468-030
CIN LEAKAGE TO GND (nA)
CAPACITANCE ERROR (fF)
6
4
2
0
–2
–4
–6
–8
–10
–200 –150 –100 –50 0 50 100 150 200
3.3V
5V
Figure 13. Capacitance Input Error vs. Leakage Current to GND,
CIN(+) to EXC =4 pF, CIN(−) to EXC = 0 pF,
VDD=3.3 V and 5 V
10
0.0001
1 100000
05468-029
PARALLEL RESISTANCE (MΩ)
CAPACITANCE ERROR (pF)
1
0.1
0.01
0.001
10 100 1000 10000
Figure 14. Capacitance Input Error vs. Resistance in Parallel
with Measured Capacitance
0
–10
07
05468-031
SERIAL RESISTANCE (kΩ)
CAPACITANCE ERROR (fF)
–2
–4
–6
–8
123456
Figure 15. Capacitance Input Error vs. Serial Resistance,
CIN(+) to EXC = 21 pF, CIN(−) to EXC = 23 pF, V
DD
= 5 V,
the Same Configuration as in Figure 34.
0.2
–1.0
2.5
5.5
05468-032
V
DD
(V)
CAPACITANCE ERROR (fF)
0
–0.2
–0.4
–0.6
–0.8
3.0 3.5 4.0 4.5 5.0
Figure 16. Capacitance Input Power Supply Rejection (PSR),
CIN(+) to EXC = 4 pF, the Same Configuration as in Figure 30
0.20
–0.20
0 128
05468-033
CAPDAC CODE
CAPDAC CODE DNL (pF)
0.15
0.10
0.05
0
–0.05
–0.10
–0.15
16 32 48 64 80 96 112
Figure 17. CAPDAC Differential Nonlinearity (DNL)