Hello,
We are using the ADS1294 in a 1 and 2 channel EMG amplifier application. We have a dedicated front-end and use the ADS1294 merely as a high-end AD-converter. The gain of the input stage is set 1x, supply voltage is 2.8V, high res mode, 8kSPS. Input signal is symmetrical. Internal ref voltage is 2.4V.
The maximum differential input voltage is 2V (4Vtt). According to eq 5, page 56, the CM range is 1.6V > CM > 1.2V. So initially we set the CM voltage to 1.2V. But with this CM voltage the undistorted input range is only 2 Vtt. Only when we increased the CM voltage to 1.6V the undistorted input range is 4Vtt.
How to explain this?