High Speed Operational Amplifier

[humanfly]

Hi Eric

Thank you very much.

Option 2 is actually my next requirement to meet(spcs 4), . It is a big big help.

 

[ericgibbs]

hi,
This is the AC analysis with +/-0.9v, with a 1Vsignal and 0V offset.

Is this what you are asking.???

 

[humanfly]

Hi Eric

Sorry about keep on disturbing you.

It should be like attached graph. Because when you close loop you amp, the gain is 1 and. output should follow input with 1V p-p. Isn’t is?

Kindly correct me if I am wrong. I will get advice from my professor too. If I found it, I will post .asc file.

Thank you for helping me.
God bless you.

 

[ericgibbs]

Hi Eric

Sorry about keep on disturbing you.

It should be like attached graph. Because when you close loop you amp, the gain is 1 and. output should follow input with 1V p-p. Isn’t is?

Kindly correct me if I am wrong. I will get advice from my professor too. If I found it, I will post .asc file.

Thank you for helping me.
God bless you.

hi,
The plot you posted has the Time Scale obscured, cannot see it, so I have assumed a 500KHz 1Vppk Sine wave input.
As you can see there is some instability in the amp, I have also attached the FFT

EDIT:
Using a 100KHz sine wave input, gives image #3, which matches your 'doc' file plot

 

[humanfly]

Hi Eric

That is the one I am looking for. Thank you so much. Sorry, I did not reply yesterday.
I had lesson and checked with my friends too. I have one few initial mistakes in my first circuit.

Thank you

 

[humanfly]

Sorry, i forgotten to let you know time scale of the previous graph. Please see the attachment. It is "us".

Thank you

 

[ericgibbs]

I need one more help. Could you teach me how to set up for “transient response of voltage follower?
Kindly see the attaché doc file for reference.
I should find 1% settling time, (t)settle for a volt step <500ns
Thank you

hi,
If you mean the LTS settings for the Transient Response plot I posted, look at these images.

I will look at the response for a 1V step voltage, let you know.

 

[ericgibbs]

hi,
Two transient pulse plots, using a 0.5V step and the other using -0.5v to +0.5v input step.

I have used the 'double cursor' option to show a 'rough' measurement of the over/under shoot decay time.

 

[humanfly]

hi,
Two transient pulse plots, using a 0.5V step and the other using -0.5v to +0.5v input step.

I have used the 'double cursor' option to show a 'rough' measurement of the over/under shoot decay time.

Wow Amazing. Thank you thank you.

I will use your method on my new circuit. (So sorry for the confusion)
I wish I can go ahead with your help.


Thank you again.

 

[ericgibbs]

hi,
With such a high open loop gain, the amplifier is switching from +/-Vout saturation, as it will.!

Its acting as a comparator because of the small imbalances in the circuit.

Exactly which parameter of the open loop amplifier are you trying measure when you apply the DC analysis, with one input connected to a fixed 0.63v.?????

 

[humanfly]

hi,
With such a high open loop gain, the amplifier is switching from +/-Vout saturation, as it will.!

Its acting as a comparator because of the small imbalances in the circuit.

Exactly which parameter of the open loop amplifier are you trying measure when you apply the DC analysis, with one input connected to a fixed 0.63v.?????

Hi Eric

Oh Ok!

The objective of the project is to design and simulate an operational amplifier which can
be used for high speed switched capacitor filters, in which the load is purely capacitive.

 

[ericgibbs]

hi,
Are you waiting for more input from me or is the project complete.???

The Sims I posted should be enough to determine the approximate parameters of the amplifier.

 

[humanfly]

hi,
Are you waiting for more input from me or is the project complete.???

The Sims I posted should be enough to determine the approximate parameters of the amplifier.

Hi Eric

I am in process to put all together and writing the report. Yes, your posts are more than enough.
I really really appreciate!

Thank you.

Will update you if anything.

You take care

 

[xu3]

hi,
Two transient pulse plots, using a 0.5V step and the other using -0.5v to +0.5v input step.

I have used the 'double cursor' option to show a 'rough' measurement of the over/under shoot decay time.

hi,
interesting OpAmp stuff ^ ^
i was wondering how u determine M7 W/L? was that a resister replacement? or current mirror?
pls enlighten me thanks.
sorry i'm abit new here