JAJSOX0A March 2024 – June 2024 ADS127L18
ADVANCE INFORMATION
Input signals occurring near the modulator sampling rate, fMOD = fCLK / 2, alias to the pass band, resulting in data errors. When aliased, the frequency errors are unable to be removed by post processing. An analog antialias filter at the ADC inputs removes out-of-band frequencies from the input signal to prevent frequency aliasing into the pass band. The required filter order of the filter is dependent on the selected OSR and the target value of signal attenuation at fMOD. A large value of OSR provides more frequency range between the fDATA Nyquist frequency and fMOD for filter attenuation. For example, for OSR = 128, more than two decades of frequency separates fDATA and fMOD. With a corner frequency of fDATA, a third-order, 60dB per decade filter provides a 120dB alias rejection at fMOD.