Pspice inverting opamp input resistance

[hoheiho]

I am working with Pspice student verison 9.1. Is there any simply way i can find out the input and output resistance in pspice?

basiclly my opamp is same as this without Rg resistor

Thank you

 

[Antiphon]

I don't use pspice, but you can look at the circuit and immediately see the input impedance is Ri and the output impedance is zero.

 

[hoheiho]

sorry.. i mean the Rin in opamp

 

[hoheiho]

someone said it can find in output file...could anyone tell me how can i do it?

 

[MisterX]

What you can do is open up the library with the OrCAD Model Editor (a separate program) and find the part. I found something like this.

*-----------------------------------------------------------------------------
* connections:   non-inverting input
*                |  inverting input
*                |  |  positive power supply
*                |  |  |  negative power supply
*                |  |  |  |  output
*                |  |  |  |  |
.subckt uA741    1 2 3 4 5
*
  c1   11 12 8.661E-12
  c2    6  7 30.00E-12
  dc    5 53 dx
  de   54  5 dx
  dlp  90 91 dx
  dln  92 90 dx
  dp    4  3 dx
  egnd 99  0 poly(2) (3,0) (4,0) 0 .5 .5
  fb    7 99 poly(5) vb vc ve vlp vln 0 10.61E6 -10E6 10E6 10E6 -10E6
  ga    6  0 11 12 188.5E-6
  gcm   0  6 10 99 5.961E-9
  iee  10  4 dc 15.16E-6
  hlim 90  0 vlim 1K
  q1   11  2 13 qx
  q2   12  1 14 qx
  r2    6  9 100.0E3
  rc1   3 11 5.305E3
  rc2   3 12 5.305E3
  re1  13 10 1.836E3
  re2  14 10 1.836E3
  ree  10 99 13.19E6
  ro1   8  5 50
  ro2   7 99 100
  rp    3  4 18.16E3
  vb    9  0 dc 0
  vc    3 53 dc 1
  ve   54  4 dc 1
  vlim  7  8 dc 0
  vlp  91  0 dc 40
  vln   0 92 dc 40
.model dx D(Is=800.0E-18 Rs=1)
.model qx NPN(Is=800.0E-18 Bf=93.75)
.ends

Using this model, it may be possible to draw out the subcircuit and solve for input resistance.

Alternatively, you could attempt to run a simulation and divide input voltage by input current.