I am looking into system architecture and requirements for a data acquisition system. I would like to start putting together an architecture for a signal chain that will condition incoming differential low voltage signals (sub-milivolt) with a digitally controlled low pass filter corner freq of 10kHz minimum to 200kHz maximum. These limits can be adjusted up and down, but just picked 10-200 as that is my corner frequency of interest.
So the high level blocks are as follows:
diff input -> adjustable low pass filter fc -> analog gain control -> ADC
I know this is pretty loose right now, but I've had a hard time making progress on parts/architecture for the adjustable low pass filter block. Some of the rough requirements are below.
1. Input signal strength (signal from sensor) less than 1mV (more like ~100mV)
2. Analog power for this signal chain can be 3.3Vdc but it would be great if the analog signal chain AND ADC were > 3.3V (5V or more).
3. Gain of 1 to 100V/V minimum implemented in analog hardware.
I will need to condition and sample a differential bridge type sensor that outputs a small voltage. The conditioning analog hardware will need to provide anti-aliasing filtering that is adjustable and an adjustable gain with both of these controlled digitally. What product families (amps or otherwise) should I be studying to put something like this together? Ideally I would not have a split supply design and either use 0-3.3V or greater for the analog power supply and sensor biasing as well as the ADC reference. I think the first step is to look into how to do the adjustable low pass filter (digitally controlled) and go from there. I can provide more detail.
Any input is helpful!