[quote author="Rochey"]i've said it before (and in emails) - the PGA2500 seems to be getting a lot of attention, however, you will need some digital mumbo jumbo to get it working.
In terms of noise performance and distortion etc. it is below other 'input' devices available on the market (I think it's because there isn't a need for a gain set resistor)
However, for single channel work, it may not be suitable because of the need for a microcontroller to make it work.
If however, you have a multichannel system (e.g. an 8 channel mic pre and ADC) then you might find it perfect.
Other devices that come to mind are the OPA1632.
Cheers
R[/quote]
Why would the absence of an external gain set resistor lower noise and distortion?
It does look like an o.k. part, with about 1.3nV/root Hz of voltage noise and fairly high current noise (notice how the noise performance degrades with 150 ohm source Z compared to zero source Z). Hardly state-of-the-art noise compared to discrete designs, but good for an IC. The requirement it talks to a micro is a little annoying, if only because you would like to keep those noisy buggers out of your system if possible---it's a challenge to confine the digital hash.
It would be nice to see a spectral plot of the noise and distortion to see where the sideband energies are, as well as some IM plots.
All in all a good effort and undoubtedly a convenient building block for uC-based systems.
