Programming instructions

Opamp
 National Instruments Corporation 5-5 Multisim Component Reference Guide
A third stage is introduced by specifying the location of the second pole:
where
5.1.3.2 Virtual 5-Terminal Opamp
This is a more complex simulation model that takes into account the supply voltages of the
opamp. This model is a differential input, single output model based on the Boyle-Cohn-
Pederson macro model, which includes the supply voltage connections. This model supports
second order effects such as common-mode rejection, output voltage and current limiting
characteristics of the opamp in addition to the first order effects.
The modeled opamp parameters are:
• open loop gain
• input resistance
• output resistance
•slew rate
• unity-gain bandwidth
f
u
= unity-gain bandwidth in hertz; i.e., the
frequency at which the open-loop voltage
gain equals 1.
f
P2
= second-pole frequency. A third stage may
be introduced by specifying the location of
a second pole in hertz.
C
C
= compensation capacitance, which shifts
the dominant pole to the left in the
frequency response. Its value is typically
30-40 picofarads.
SR = slew rate, which is the rate of change of
output voltage (in V/s) in response to a
step input.
C
Rf
R
RR
I
AV
R
P
OUT
IN
2
22
2
3
3
13
3
1
2
1
=
∗∗
=
=
=
∗
π
kΩ
/
ComponentRef.book Page 5 Thursday, December 7, 2006 10:12 AM