1.4.2 Differential Input with Gain Stage

This setting is almost identical to differential input without gain stage. With this setting the gain stage is inserted in the signal path for this channel, providing up to 64 times amplification of the differential input signal. Maximum sampling speed while using the gain stage is 1 Msps.

Figure 1-4. Differential Input with Gain Stage
Note: The gain stage does not load the input; hence external signal sources will see very high input impedance for channels that use the gain stage. This is useful for measuring weak signal sources. More details can be found in the data sheet for the specific device.

The voltage on any of the two inputs can be between GND and VREF, but the difference between them must not be larger than VREF/GAIN because this will saturate the ADC and the converted value will only equal the top value of the ADC.