JAJSOX0B March 2024 – November 2024 ADS127L18
PRODMIX
Input signals occurring near the modulator sampling rate (fMOD) alias to the pass band resulting in data errors. When aliased, the errors cannot be removed by post processing. If these signals are present, an analog low-pass filter at the ADC input removes the out-of-band frequencies to reduce aliasing. The order of the anti-alias filter depends on the OSR value and the desired level of attenuation. Large values of OSR provide large frequency ranges between the Nyquist frequency and fMOD for the filter to attenuate the signal. For example, for OSR = 128, more than two decades of frequency separate fDATA and fMOD. With a corner frequency = fDATA, a third-order, 60dB per decade filter provides a 120dB alias rejection at fMOD.