First sorry for my English. I have a problem. In short time I have to make a simple frontend for sapflow sensor. The measuring value will be recorded by datalogger. I have two thermocouplers but only one analog input in datalogger. Unfortunatelly I have limited access to Analog Devices parts. For example there is ADG417 and AD620 at fingertips. Here are my conditions:
-single supply: 5VDC or 12VDC
-logger input voltage range: 0..5V/16bit resolution
-resolution: 10uV (from sensor voltage)
-sampling frequency: one per hour
There are two circuits on pictures below. Please tell me are these circuits correct? I know that sapflow1.png is a worse solution but there is only one AD620. Maybe the ADG417 noise aren't to big to receive 10uV resolution. Which one I should to choose? Maybe some another one?