Author Topic: PSPICE Simulation: Ideal Opamp vs uA741  (Read 5903 times)

0 Members and 1 Guest are viewing this topic.

Offline onemilimeter

  • Frequent Contributor
  • **
  • Posts: 314
PSPICE Simulation: Ideal Opamp vs uA741
« on: July 07, 2011, 10:35:09 am »
I wish to study the step response of the post signal conditioning circuit (differential to single-ended plus low pass filter) as shown in attached figure (Fig. 21). The differential output of the ACPL-790x is 0~2.5V (attached figure, Fig. 12). Since Cadence PSPICE Schematic (v9.1) does not have the PSPICE model for TL032A, I choose uA741. With ideal opamp model, the simulation result (see attached figure) looks ok. However, with uA741, the simulation result looks weird. Does anyone know why the outputs with ideal opamp and uA741 are so much different?

Cheers.
 

Offline saturation

  • Super Contributor
  • ***
  • Posts: 4788
  • Country: us
  • Doveryai, no proveryai
    • NIST
Re: PSPICE Simulation: Ideal Opamp vs uA741
« Reply #1 on: July 07, 2011, 12:26:21 pm »
Because the 741 is not ideal, what you see are the simulated real world response.
Best Wishes,

 Saturation
 

Online ejeffrey

  • Super Contributor
  • ***
  • Posts: 1932
  • Country: us
Re: PSPICE Simulation: Ideal Opamp vs uA741
« Reply #2 on: July 07, 2011, 01:31:41 pm »
I took a look at the uA741 data sheet, and looked under "slew rate limit."  The typical slew rate is listed as 0.5 volts/microsecond and your triangle wave has a slope of around... 5 volts/ 10 microseconds.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf