AD841
REV. B
–6–
INPUT CONSIDERATIONS
An input resistor (R
IN
in Figure 20) is recommended in circuits
where the input to the AD841 will be subjected to transient or
continuous overload voltages exceeding the ±6 V maximum dif-
ferential limit. This resistor provides protection for the input
transistors by limiting the maximum current that can be forced
into the input.
For high performance circuits it is recommended that a resistor
(R
B
in Figures 19 and 20) be used to reduce bias current errors
by matching the impedance at each input. The output voltage
error caused by the offset current is more than an order of mag-
nitude less than the error present if the bias current error is not
removed.
AD841 SETTLING TIME
Figures 22 and 24 show the settling performance of the AD841
in the test circuit shown in Figure 23.
Settling time is defined as:
The interval of time from the application of an ideal step
function input until the closed-loop amplifier output has
entered and remains within a specified error band.
This definition encompasses the major components which com-
prise settling time. They include (1) propagation delay through
the amplifier; (2) slewing time to approach the final output
value; (3) the time of recovery from the overload associated with
slewing and (4) linear settling to within the specified error band.
Figure 19a. Inverting Amplifier
Configuration (DIP Pinout)
Figure 20a. Unity-Gain Buffer Amplifier
Configuration (DIP Pinout)
Figure 19b. Inverter Large Signal
Pulse Response
Figure 20b. Buffer Large Signal
Pulse Response
Figure 19c. Inverter Small Signal
Pulse Response
Figure 20c. Buffer Small Signal
Pulse Response
OFFSET NULLING
The input offset voltage of the AD841 is very low for a high
speed op amp, but if additional nulling is required, the circuit
shown in Figure 21 can be used.
Figure 21. Offset Nulling (DIP Pinout)
