1 Hz Low Pass Filter

[fourierpwn]

Hi all,

A typical measurement setup used to measure 1/f noise is to use a 1 Hz low pass filter in order to filter out any noise that is present on the DC bias voltages from a given SMU and obtain "clean" DC.

All attempts at building a simple RC filter have not yielded results that seem correct. This filter is not specific to the type of measurements it is being used for, so essentially I am just after a ? 1Hz LPF to clean up some DC voltages. Sounds simple enough (probably is, I'm just too noob) but I would appreciate as far as practical designs.

 

[Benta]

At frequencies that low, component values get so large that it's practically unmanageable and you get into all sorts of leakage and other parasitic problems.
If at all possible, I'd recommend an active filter, but even there you'll have to watch out for parasitics.

[bson]

Use an active filter for such low frequencies!

[eliocor]

Switched capacitor filters?
https://www.maximintegrated.com/en/products/analog/analog-filters.html
http://www.linear.com/product/LTC1059
http://www.linear.com/parametric/Filter_Building_Blocks
http://uk.farnell.com/c/semiconductors-ics/filters-active/switched-capacitor-filters

[edit] @Benta: sorry, I was in a hurry and I didn't take care of the requirement for 1/f measurements!!!

[Benta]

If you read the OP, the goal is to measure 1/f noise. I'd expect any kind of switched filter to counteract that goal. Just sayin'

[jpanhalt]

How about lead-acid batteries?  We ran our Beckman DU spectrometers from them.