LTC1533 low noise output

[alimjoco]

Hi Experts,

Do anyone have the chance to measure the low noise output of LTC1533 (100uV peak to peak)? I tried measuring the low noise output of this part and it seems I'm getting 5x worse--500uV peak to peak. I appreciate anybody's help.

Here's the link I'm pertaining:
http://cds.linear.com/docs/Application Note/an70.pdf

Application note 70 from LTC-jim williams

 

[alimjoco]

Is there anyone who have replicated its results using the sAME DEVICE?

 

[mtwieg]

Are you using a similar measurement setup? Most scope inputs have a noise floor of at least 1mVrms, which is why they put a low noise preamplifier before the scope. Are you using only coaxial connections?

The app note spends a lot of time detailing how to do the measurement, and they're not kidding around when they say those measures are necessary when trying to measure such performance.

 

[raylay]

Do you have keep a good grounding when measure the signal?

 

[alimjoco]

measuring very low ripple and noise in switchers

guys, is it required that the power source in powering the dut is very low noise if im measuring like 100uV ripple less? Im using a bench top E3631A power supply. Is it better to use a battery?i need 12v supply for my dut

Threads merged. You will get better answers if there is a connection between your questions, don't start new threads to continue the same conversation [alexan_e]

 

[mtwieg]

Re: measuring very low ripple and noise in switchers

The reason I mentioned the source in your other thread (you only need one...) isn't so much about noise, but that it doesn't have its own switching ripple which contributes to the output seen on the DUT (the supply you're testing). You want the DUT to be operating at an absolutely constant duty cycle, so the input voltage should be solid. So yeah a battery would be nice, if it works. But any supply can probably be made to work with proper filtering. But be wary of benchtop switching supplies.