Datasheet

TLE208x, TLE208xA, TLE208xY
EXCALIBUR HIGH-SPEED JFET-INPUT
OPERATIONAL AMPLIFIERS
SLOS182B – FEBRUARY 1997 – REVISED JUNE 2001
64
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
input characteristics
The TLE208x, TLE208xA, and TLE208xB are specified with a minimum and a maximum input voltage that if
exceeded at either input could cause the device to malfunction. Because of the extremely high input impedance
and resulting low bias current requirements, the TLE208x, TLE208xA, and TLE208xB are well suited for
low-level signal processing; however, leakage currents on printed-circuit boards and sockets can easily exceed
bias current requirements and cause degradation in system performance. It is good practice to include guard
rings around inputs (see Figure 74). These guards should be driven from a low-impedance source at the same
voltage level as the common-mode input.
V
I
R2
R1
V
I
R4
+
–
V
O
R3
V
I
+
–
V
O
V
O
+
–
R3
R4
R2
R1
Where
Figure 74. Use of Guard Rings
TLE2081 input offset voltage nulling
The TLE2061 series offers external null pins that can be used to further reduce the input offset voltage. The
circuit of Figure 75 can be connected as shown if the feature is desired. When external nulling is not needed,
the null pins may be left unconnected.
+
–
V
CC–
N2
N1
100 kΩ
5 kΩ
IN–
IN+
OUT
Figure 75. Input Offset Voltage Nulling