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LM7171: Propagation delay

Danilo A.
Mastermind 26710 points
Part Number: LM7171
Other Parts Discussed in Thread: THS4012, THS4022, LM6172, OPA862

Hi Team,

A customer would like to design a single to differential stage using the LM7171 opamp. Since the LM7171 come in single channel package, how good is the propagation delay matching to be between two such opamps?

In his application he will have 20ns rise/fall times, so the propagation delays of the 2 opamps (5ns typical) should not vary drastically. He had looked for 2-channel opamps that would have very close matching, being in the same die, but the results were not as good as with LM7171 (for example LM6172 and THS4012/THS4022).

He don't mind about the exact number of the propagation delay, he just need them to be close for the two discrete opamps. 

Regards,

Danilo

  • 0
    TI__Genius 15555 points

    Hello Danilo,

    Delay should be fairly similar, however will vary slightly since Aol response varies between devices. The delay would also be affected by the configuration of each device. 

    On another note has the customer considered using an FDA or the OPA862?

    Best,

    Hasan Babiker

  • 0
    Guru 48395 points

    Well Danilo, 

    Delay? 

    1. Package prop delay, very low and matched

    2. Device delay or really phase shift, need to have the same noise gain, but if you do the phase responses should be close on a single die dual. 

    3. Why use a dual op amp when there are such a wide selection of FDA's that can be set up for single to diff out directly with exceptional matching on the two outputs