Differential ADC: What is it good for?

[juanfhj]

I've seen an application note where a unipolar signal is buffered by two op amps, one inverting and one non-inverting, for a differential ADC (AD7688) to read. Why is this any improvement over a standard ADC? I guess it would be if the two amps are far away from the ADC, but is it any good if they're close?

 

[FvM]

ADC with differential input generally give higher linearity and interference suppression. Some can be optionally operated single ended with reduced performance. As far as I understand, AD7688 is not intended for single ended operation.

 

[juanfhj]

Thanks. Any suggestion for a 16-bit diff ADC besides the AD7688? My input comes from a logarithmic amplifier (AD606 ). It has a standard voltage output and a differential current output, and I'm deciding whether sticking with the standard output or using the differential one. I'm also considering the diff ADC ADS8320. I guess it must be a SAR because I want it to operate at 30+ KHz and the input to the log amp is multiplexed.