Input Gain and Offset

The AFE has a built-in programmable gain amplifier (PGA) and programmable offset per channel through a DAC.

The programmable gain amplifier can be set to gains of 1, 2 and 4 and can be used for single-ended applications or for fully differential applications.

The AFEC can apply different gain and offset on each channel.

The gain is configured in the GAIN field of the Channel Gain Register (AFEC_CGR) as shown in the following table.

Table 1. Gain of the Sample-and-Hold Unit
GAIN	GAIN (DIFFx = 0)	GAIN (DIFFx = 1)
0	1	1
1	2	2
2	4	4
3	4	4

The analog offset of the AFE is configured in the AOFF field in the Channel Offset Compensation register (AFEC_COCR). The offset is only available in Single-ended mode. The field AOFF must be configured to 512 (mid scale of the DAC) when there is no offset error to compensate.To compensate for an offset error of n LSB (positive or negative), the field AOFF must be configured to 512 + n.

Figure 1. Analog Full Scale Ranges in Single-Ended/Differential Applications Versus Gain