Sinewave Amplitude Excitation stage ADuCM350

Hi,

Can you try changing your RTIA value to 1000. I recommend measuring the actual RTIA as well.

#define RTIA (33000) change to --> #define RTIA (1000)

regards,

Mark

Hi,

I have made some tests setting directly the DAC value and I have found out that the amplitude of the sinusoid generated by the trasmit stage decrease heavily increasing the output frequency. For example, with a DAC value of 1023, at 15kHz the peak to peak magnitude of the sinusoid generated is about 0.77 V, while with the same DAC value but an output frequency of 50kHz, the peak to peak magnitude of the sinusoid generated is about 0.5 V. Is this something already known? Do you know what could be the reason for this behaviour? Does the excitation stage have some bandwidth limitations in the ADC allowed frequency range (about 80 kHz)?

Thank you

Best regards

Ivan 

Hi,

There is a 3^rd order LP RCF filter on receive channel which causes attenuation. This is centered at 50kHz but can have +/-20% tolerance.So the 3rd order roll off could start happening at ~35 kHz.

-Mark

Hi,

There is a 3^rd order LP RCF filter on receive channel which causes attenuation. This is centered at 50kHz but can have +/-20% tolerance.So the 3rd order roll off could start happening at ~35 kHz.

-Mark

I did not notice that filter.

Thank you