PXI 5421 Minimum amplitude for a sine wave

[LuisFuentes]

Hi,

I need to generate a signal 1151200Hz, 50uVpp, Sine wave signal and inject this signal into one of our products, I haven tuse the PXI 5421, but we have one available.

I was checking the specifications but looks like is not able to meet the 50uVpp amplitude. this is a pretty expensive equipment but it looks like is not even able to reach 2mvPP, looks like the minimum is 5.64mvPP. 

in the comments section looks like you can go lower, and Im trying to get help to se how lower can I go, thanks for the support.

[kirsch]

The minimum amplitude is assuming a digital waveform that uses the full range of the DAC. You can always sacrifice DAC resolution in order to get a signal with a smaller amplitude.

In the case of the 5421 there are multiple ways to accomplish this.

If you are using NIFGEN_ATTR_OUTPUT_MODE set to NIFGEN_VAL_OUTPUT_ARB (Arbitrary Waveform Mode) then create your waveform so it spans less than the full -1.0 to 1.0. Say you want to use only 10% of the range - make your waveform go from -0.1 to 0.1.

Similarly, if you are using NIFGEN_ATTR_OUTPUT_MODE set to NIFGEN_VAL_OUTPUT_FUNC (Function Mode) then use NIFGEN_ATTR_FUNC_WAVEFORM set to NIFGEN_VAL_WFM_USER, and write your function using niFgen_DefineUserStandardWaveform() where the data spans from -0.1 to 0.1.

Alternatively, you could set NIFGEN_ATTR_DIGITAL_GAIN to 0.1 (again using my 10% example). This multiplies the digital data going into the DAC allowing you to "make your waveform smaller".

I hope this makes sense, and the floor noise on the analog output is alright for your application. Note I'm using the symbol names for the C API but this applies to all the supported languages and you should be able to map it to those symbols.

[Henrik_Volkers]

Ever heard of attenuators?

Assuming a 50 Ohm chain and (only) 1.1 MHz you can get them quite  cheap.  (in BNC or SMA .... )

Get a 20 db  and a 40 db attenuator  (lower the amplitude by faktor 10, resp. 100 )  , if needed you can put them in a chain ...