NI 9260, 24-bit Analog Ouput Module - Noise Measurment

[cjs7]

I'm using a NI 9260, 24-bit Analog Output module in a cDAQ-9171 USB chassis and looking at the idle channel noise on a spectrum analyzer (SRS SR785). The data sheet quotes 10 uVrms (I'm assuming this is measured from ~DC up to 23 kHz, which is the bandwidth of the device), but I am measuring much worse. I see ~40 uVrms from ~DC to 23 kHz.

Could this have anything to do with using the USB chassis?

Has anyone out there performed a similar measurement on this device?

This seems like an excessive amount of noise for a 24-bit DAC.

[hmiraquesa]

Hi cjs7,

Are you measuring the noise on a unwired channel? If this is correct this is a common behavior on DAQ devices. Maybe you can give more information about the appliaction.

Regards

miraquesa

[cjs7]

Hi miraquesa,

What do you mean by "unwired channel"? I am measuring the noise on channel 1 by opening up a test bench for the device in MAX and telling it to output 0 V to channel 1.

A potential application for this is to generate arbitrary voltage waveforms (linear ramps and single valued voltages). Basically, we have an experimental sequence that consists of a bunch of stages where a variety of voltage-controlled components (VCO's, current supplies, etc.) are ramping or holding their outputs constant. Low noise is extremely important for some of our voltage-controlled current sources.

[hmiraquesa]

Hi cjs7,

I apologized for the time. Did you already try the instructions on the specs manual to reduce the noise? You will find the information on page 4, just follow the next link.

http://www.ni.com/pdf/manuals/376927a.pdf

If  you output another value instead of 0 V you get the same behavior?

Regards,

Héctor Miranda

Applications Engineering

National Instruments

www.ni.com/support