Hi, I am currently looking for an amplifier for a signal conditioning circuit. The input would be differential from 0-20mV and the output would be amplified to 0-5V and sent to an ADC for further processing. I would like to ask whether it would be better to have a fully differential amplifier or a single-ended output instrumentation amplifier like the INA828.
Hi Esther,
You do not specify the frequency of the input signal nor the input common-mode voltage, Vcm.
Assuming the input signal frequency is below 100kHz and Vcm=0, you could use INA828 powered by dual +/-5V or higher supply voltage - see below.
Of course, in order for the output voltage to swing all the way to 5V for Vin_diff of 20mV, the positive supply voltage would need to be at least 5.1V - see below.
Having said that, if the Vcm=0 and the input frequency is below 50kHz, a simpler and less expensive solution would be to use OPA392 on a single supply OPA392 - see below.
In case the input common-mode voltage, Vcm, is not zero, you could use OPA392 as a difference amplifier as shown below.
Please keep in mind that no op amp output may swing all the way to its rails and thus in case of OPA392 using 5V single supply the linear output voltage range is between 50mV to 4.95V (see OPA392 datasheet for AOL conditions). Thus, if you absolutely need for the output to swing linearly between 0 and 5V you must use a negative supply of at least -50mV (see LM7705) and a positive supply of at least 5.05V
Below I have attached Tina-TI circuit schematics for your convenience.
