switched-capacitor circuit

[Howard Houston]

Hi, in Multisim 10 does not work the switched-capacitor circuit with analog switches and opamps. There is no voltage on oscilloscope. Opamps are ideal. In what a problem? In fact the circuit in Electronics Workbench 5.12 works. The circuits are attached.

[lacy]

Try using the other op amp called the 3T_Basic. You can still adjust the parameters from the edit model button in the component properties. Once in the model edit window look to the very bottom where there is a statment call "PARAMS" this is where you modify it to suit your application.

I have tried everyway I know of to get the original one to work,  but apparently there is something not right about the model otherwise it would work with no questions asked. This issue with the op amps have been reported numerous times on the forum and I hope it will be taken care in future updates as it is now becoming a real problem for everyone.

I hope I have helped solve the problem with your circuit.

Message Edited by lacy on 03-22-2008 07:50 PM

[Howard Houston]

lacy, thanks, the circuit works. I have created a component 3T_Basic in user database with following params (from EWB 5.12):

.SUBCKT op_ideal 1 2 3
    Vos 4 1 DC 0V
    Ib1 4 0 0A
    Ib2 2 0 0A
    G1 0 5 4 2 100m
    G2 0 6 5 0 100
    G3 0 3 6 0 100
    Ri 4 2 10Gohm
    R1 5 0 1Kohm
    R2 6 0 1ohm
    R3 3 0 1ohm
    C1 5 0 159.155p
    C2 6 0 1.59155e-33
.ENDS

[swsw]

Hi, I am trying to do an AC analysis for my switched-capacitor filter circuit to look at the frequency response. However, I do not think the output is right. Is there a way to do this kind of simulation and verify my circuit using Multisim?
Thank you.

[lacy]

Probably a dumb question here, but have you tried the AC Anaysis under SIMULATE>ANALYSIS menu? If you have already been there done that, then there is the option of the Bode Plotter which will plot the response curve of the circuit.

Just so you will know, when I simulated your ciruit I got what I thought was a correct waveform. I was seeing a staircase type sine wave that was phase shifted from the original input waveform. I am not sure this is what you were shooting for, but I thought I would let you know what I was seeing.

I hope this helps.