LM98725: CDS Gain and PGA

Taemin Ahn

Intellectual 795 points

Part Number: LM98725

Hi team

As shown in the figure, the CDS Gain Block (red) and the PGA Gain Block (blue)

It is divided and marked.

The physical behavior of CDS Gain and PGA Gain seems to be different

Please explain the physical behavior of the two gains.

Thnaks,

over 5 years ago

0 Aaron Goodson over 5 years ago

TI__Expert 6330 points

Hi,

I have notified our expert regarding this topic. Please expect a response by 12/6/18.

Thanks,
Aaron

0 Costin Cazana over 5 years ago

TI__Expert 4940 points

Hi TM,

The first one -GDS Gain is a buffer with Gain=1x/2x in order to get the max dynamic range at the ADAC input.
The second gain is used to calibrate white level. This gain is calibrated after the offset correction( black level)
PGA gain curve is non-linear for optimal performances.

Regards,
Costin

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LM98725: CDS Gain and PGA