AD795
10kΩ
+V
S
0.1µF
100
20V
5µs
100
90
10mV
500ns
10kΩ
V
IN
2
7
90
AD795
3
4
6
V
OUT
C
L
100pF
10
0%
10
0%
R
L
10kΩ
0.1µF
–V
S
5V
Figure 24. Unity Gain Inverter
Figure 25. Unity Gain Inverter
Large Signal Pulse Response
Figure 26. Unity Gain Inverter
Small Signal Pulse Response
+V
S
0.1µF
20V
100
5µs
100
90
20mV
500n s
2
V
IN
3
4
7
90
AD795
6
V
OUT
C
L
100pF
10
0%
R
L
10kΩ
0.1µF
10
0%
–V
S
5V
Figure 27. Unity Gain Follower
Figure 28. Unity Gain Follower
Large Signal Pulse Response
Figure 29. Unity Gain Follower
Small Signal Pulse Response
MINIMIZING INPUT CURRENT
The AD795 is guaranteed to 1 pA max input current with
±
15
volt supply voltage at room temperature. Careful attention to
how the amplifier is used will maintain or possibly better this
performance.
The amplifier’s operating temperature should be kept as low as
possible. Like other JFET input amplifier’s, the AD795’s input
current will double for every 10°C rise in junction temperature
(illustrated in Figure 6). On-chip power dissipation will raise the
device operating temperature, causing an increase in input
current. Reducing supply voltage to cut power dissipation will
reduce the AD795’s input current (Figure 4). Heavy output
loads can also increase chip temperature, maintaining a
minimum load resistance of 10 kΩ is recommended.
–8–
REV. A
AD [ ANALOG DEVICES ]
