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THS4522 offset shift

Mark Parsons
Prodigy 20 points
Other Parts Discussed in Thread: THS4522, THS4521

I'm using the THS4522 as an ADC front end filter.

Issue is the output of amplifier-2 produces an output offset shift of several mV at certain temperatures.

On a 3v3 supply, 1.25v common mode inputs, zero differential input, at ~1C and at ~40C the output differential signal suddenly increases or decreases ~3mV.

The jump is quite repeatable.

The amplifier-1 does not do this jump.

The similar THS4521 amplifier does not do this jump. 

Any thoughts?

  • 0
    TI__Expert 4115 points

    Mark,

    This sounds like a statistical outlier or bad part. The offset on the device is tested at 25C and if it is less than +/-2mV, it passes. But no test is done over temp. I attach Vos over temp graph made during characterization of the THS4521ID, which is a single die version where the THS4522 uses 2 die; so behavior should be same or very similar. The sampling is only 24 devices, but is statistically significant. The data shows no device behaving as you describe so that what you are seeing is not normal. The device may have been damaged somehow or is a statistical outlier.