Precise Programmable Voltage

[Stveon]

Hi all,

I am doing project on programmable voltage with step size of <1mV.
I use 16bits DAC to convert digital data to analog ouput.
The output of DAC is very noisy.

Question:
1) I notice that most of the application circuit has output and sense pin to form a KELvin contact. Do you have any sample circuit for this force and sense output?
2) Any recommend DAC that is 1channel 16bits, -10V and 10V, low noise?
3) I notice everytime power ON OFF, the output of DAC also no consistense.
Do you know how to solve this?
Thank you

 

[Papabravo]

No circuit that you build on a breadboard will achieve the performance that you seek. In order to do what you want you have to start with a carefully layed out PC board. Then you have to find and eliminate the noise sources one by one. Oh...you didn't know there were multiple sources and coupling mechanisms. There is enough material here for a PhD. At some point you will reach the noise floor where no further improvement is possible.

Just because you have 16 bits does not mean you can resolve a change of 1 LSB which would be about 300 microvolts. This is why companies that make laboratory instruments can charge big bucks. To do what you are trying to do is really hard, especially on a shoestring.

Last point. Expecting a DAC to hold its value, or recall it's value, through a power cycle is totally unreasonable. DACs do not normally have non-volitile memory in them. It takes a processor to reinitialize them from non-volitile memory in the processor.