Tool/software:
Hello team,
Customer met some problems when design ADS1014-Q1, there are some questions need to check with you:
1. What is the concrete range of half the sampling frequency of the ADC;
2. What is the meaning of Unwanted signal, what is the range?
3. What is the meaning and value of fmod/2?
Thanks!
Hello Daniel,
Thank you for the questions!
1. What is the concrete range of half the sampling frequency of the ADC;
This would relate to the data rate the customer is using, the Nyquist criterion requires that the sampling frequency must be at least twice the highest frequency of the input signal or signal information will be lost.
Ex. 128sps ADC output rate would limit the input to a 64Hz.
2. What is the meaning of Unwanted signal, what is the range?
Unwanted Signals would refer to any signal that is picked up outside of the sensor signal. Potential unwanted signals could be aliasing, internal noise picked up along the sensor wiring, or external noise from electromagnetic interference (EMI) or radio frequency interference (RFI).
If the sampling frequency is less than twice the maximum input signal frequency aliasing will occur creating unwanted signals. In most cases aliasing can be mitigated through the use of a first-order resistor-capacitor (RC) filter on the analog inputs.
3. What is the meaning and value of fmod/2?
According to Section 7.3.2 of the data sheet below: The frequency at which the input signal is sampled is called the sampling frequency or the modulator frequency (fMOD). fMOD = 250kHz, fMOD/2 would equal 125kHz.
Delta-sigma ADCs are built on the principle of oversampling, where the delta-sigma modulator will average multiple readings and output its averaged result. Delta-sigma ADCs output data rates are often hundreds of times lower than the frequency fMOD due to this principle.
Regards,
Andrew
