Hello ! my friend, now i can run the ads1298 sucessfully.
But when measuring the noise of each channel, i found it a little bit noisy of channel 1-6.
the noise ampltude of ch1 to ch6 is about 190 uV. and the peak-to-peak range is less than 10uV .
When it comes to the ch7 and ch8 ,the noise amptitude is about 30uV, peak-to-peak range is also less than 10uV .
So fat I havn't found the reason .Could some one give me some advise ?（the data is even negative，it means that the INXN is a little bit higher than INXP ）
MY test condition: 25℃, sampling rate:500SPS , High Resolution mode and PGA = 1,TQFP package ;
Here are some charts which drown by EXCEL:
A student waiting for your help from GuangZhou ,CHINA.
Hello Yuji,
Welcome to the Precision Data Converters Forum! Is this a board of your own design or are you using the ADS1298 hardware from ADS1298ECGFE-PDK? It looks to me like you might actually be measuring the offset of the ADS1298 in your first graph above. The offset error can be as hign as 500uV, so your ~192uV would be in line with the data sheet specifications for the ADS1298. The Vpp of your second graph, at 500SPS, PGA = 1 in High Res mode looks good.
Regards,
Tom
Thank you TOM!
it's a board of my own design.
I think i misunderstanded the concept of input refered noise before your apply;
Would you mean that ( CHnSET BIT[ 2:0 ] = 001 for offset or noise measurement ) :
OFFSET ERROR = the absolute voltage amplitude
INPUT REFERED NOISE = the VPP value ?
Thanks you very very much!