# Does the QA 403 can do DC measures

**URL:** <https://forum.quantasylum.com/t/does-the-qa-403-can-do-dc-measures/1860>\
**Category:** Uncategorized\
**Created:** [May 7, 2025, 7:15pm UTC](https://forum.quantasylum.com/t/does-the-qa-403-can-do-dc-measures/1860 "2025-05-07T19:15:53Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Anode](https://yyz2.discourse-cdn.com/flex032/user_avatar/forum.quantasylum.com/anode/32/3543_2.png) [@Anode](https://forum.quantasylum.com/u/Anode)\
**Post date:** [May 7, 2025, 7:15pm UTC](https://forum.quantasylum.com/t/does-the-qa-403-can-do-dc-measures/1860/1 "2025-05-07T19:15:53Z")

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Hi all,

Does the QA403 can do some DC measures like the ripple form PSU ?

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**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://forum.quantasylum.com/u/matt)\
**Post date:** [May 10, 2025, 7:51pm UTC](https://forum.quantasylum.com/t/does-the-qa-403-can-do-dc-measures/1860/2 "2025-05-10T19:51:47Z")

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Hi @Anode, ripple is usually at 50 or 60 Hz, which the QA403 can readily measure. The QA403 inputs are AC coupled with a corner around 1 Hz. So, it can’t measure DC, but it can get close.

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**Author:** ![Anode](https://yyz2.discourse-cdn.com/flex032/user_avatar/forum.quantasylum.com/anode/32/3543_2.png) [@Anode](https://forum.quantasylum.com/u/Anode)\
**Post date:** [May 11, 2025, 7:19am UTC](https://forum.quantasylum.com/t/does-the-qa-403-can-do-dc-measures/1860/3 "2025-05-11T07:19:12Z")

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Hi Matt,

Many thanks to you for your reply, I thought I saw an article where you measured an LT3045 (LDO) because it is this type of regulator I am talking about.

Thanks Matt

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**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://forum.quantasylum.com/u/matt)\
**Post date:** [May 11, 2025, 2:19pm UTC](https://forum.quantasylum.com/t/does-the-qa-403-can-do-dc-measures/1860/4 "2025-05-11T14:19:48Z")

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Hi @Anode, yes, I think you are referring to the link below? Part 2 of the article showed an LT3042. But yes, you should be able to characterize the AC noise very thoroughly with a QA403. The JFET amp on the QA472 can get 10 dB deeper than the amps on the QA470. And then the QA350 was used to look at DC performance of LDO.

> **[Characterizing LDOs: Part 1](https://quantasylum.com/blogs/news/characterizing-ldos-part-1)**
>
> This is Part 1 of 3 parts.Part 2 of this article is located here.Part 3 of this article is located here. LDOs might seem to be interchangeable. And in many circuits they are. But when you are chasing the last few dB of performance in a 24-bit DAC or...