LMP7732: Group Delay / Phase Delay

Riddhee Abhyankar

Prodigy 70 points

Part Number: LMP7732

Hi ,

I want to know if it is possible to measure phase delay and group delay with Tina TI ?

If yes can you suggest the steps to plot the same ?

Thanks & Regards

Riddhee

over 3 years ago

0 Michael Steffes over 3 years ago

Guru 47485 points

Run your AC sim using a linear F sweep, there might be a utility to report phase linearity and prop delay from that, or dump the data to excel and extract from there.

0 Raymond Zhang1 over 3 years ago in reply to Michael Steffes

TI__Mastermind 47796 points

Hi Riddhee,

Can you share the schematic with us?

If you want to know exact phase delay, please follow Michael's suggestions. If you want to know the approx. phase delay, you can measure it via Tina simulation. For single pole system, The phase delay starts a decade earlier from a pole (5.73 degree) and it ends a decade after the pole (84.3 degree).

For a group delays will be a slightly complicated, but we have to see if it a closed loop or open loop system. What is your application? Are you check for the op amp stability issues or something else?

Best,

Raymond

0 Michael Steffes over 3 years ago in reply to Raymond Zhang1

Guru 47485 points

And also,

We used to do a lot of linear sweep group delay measurements on the early CFA parts which were basically linear phase, constant group delay - we were doing that for a number of reasons but keep in mind, the package delay will add to the simulated group delay - literally depends on package size - if you need that level of accuracy.

0 Michael Steffes over 3 years ago in reply to Michael Steffes

Guru 47485 points

And of course to make that package delay measurements you have to do a through calibration including the board with the I to O shorted out.

0 Riddhee Abhyankar over 3 years ago in reply to Michael Steffes

TI__Prodigy 70 points

Hi michael ,

I ran the linear frequency sweep but am unable to extract the data from the plot .

0 Riddhee Abhyankar over 3 years ago in reply to Raymond Zhang1

TI__Prodigy 70 points

Hi Raymond,

I have built the attached simulation file based on the schematic provided by the customer, as below

0456.Schematic.TSC

Its a sallen-key differential low pass design. I am unable to get the desired response at low frequencies. Can you help me identify the problem

Regards,

Riddhee

0 Raymond Zhang1 over 3 years ago in reply to Riddhee Abhyankar

TI__Mastermind 47796 points

Hi Riddhee,

Here is how you are able to extract the data from plotted out images.

What is the frequency response you want to achieve in your sallen-key filter?

Best,

Raymond

0 kai klaas69 over 3 years ago in reply to Riddhee Abhyankar

Guru 140200 points

riddhee_lmp7732.TSC

Kai

0 Riddhee Abhyankar over 3 years ago in reply to Raymond Zhang1

TI__Prodigy 70 points

Hello Raymond, Kai,

I followed your instructions for extracting the data from the Plot of AC linear frequency sweep result but the exported text files turned out to be blank