Yes, I'm a rookie trying build his first sophisticated circuit, and I'm stuck at the front end. My prototypical use-case involves the signals from amplified photodiodes in the +/- 10 volts range, connected over 50 ohm coax. Bandwidth of interest is ~ 100kHz. Past the front end, I'll be implementing a selectable DC-level offset, and lowpass filtering with this guy : LTC 1564.
The pga280 looked nice at first due to its built in, adjustable attenuation, and minimal extra parts required, but I don't think I have time now to figure out all the serial digital interfacing it would need (I have no need for the multiplexer either). Is there some simpler equivalent component out there I have overlooked?
I'm also uncertain about the per-amplifier resistors I hear are needed as a path to ground for the input current (on both amplifier inputs, I assume, given differential input). How does one calculate values for these, given use in a laboratory environment, where the circuit may need to handle input from instruments whose output impedances could differ from one to the other?
I think I can figure out the rest past that. So if any of you gurus out there feel like being charitable, a little push in the right direction would be much appreciated.
Be well, and have a great day.
--Brad
