I'm interested in using an op-amp to drive an AD7823 data convertor.
Maximum gain required is about ~30, since I can use a ref voltage as low as 1.2V on the AD7823. Required bandwidth operation is 100KHz.
I have no requirements on the op-amp except that the supply range should be between 3v to 5v. However, I do prefer to use a single supply op-amp. I'm not sure whether I should choose an op-amp with a differential output, which according to my understanding, will be more accurate (Will the AD7823 be able to work with it?) or a single ended output with a common ground to the ADC Vin- input?
After reading some application notes I became a little bit confused with all the configurations out there and would appreciate some help...
Thanks in advance,
I have moved this question to the ADC Drivers community. Someone here should be able to assist you.
EngineerZone Community Manager
Thank you Dan,
My main concern about using a single ended op-amp is noise or cross talk from other ground loops using the same ground reference point. Are there any differential-output amplifiers you can recommend that will work well with the AD7823?
On the question of using a single-ended vs. a differential-output amplifier, it generally depends on the level of precision you are trying to obtain. Since the AD7823 is an 8-bit ADC, it's LSB size with a 1.2V reference, one-half of an LSB is 2.3mV and its SINAD is 48 dB, so you won’t have any issues finding an amp that meets the noise/precision limits of the ADC.
Below is a list of op amps that you may want to consider, depending on your total set of application requirements. Since the AD7823 is a low-power ADC, I focused on quoting some low-power op amps for you.
Please let us know if you have any further questions.
Eyal, I think we need to know a little more about your application, in particular your input signal source. In particular:
A) What is the signal range (positive and negative) and impedance?
B) What is the signal referenced to i.e. is it floating, is it ground referenced or does it have a large offset.
The large LSB step size of an 8 bit converter should help you, so you need to focus on ensuring that the error sources for the amplifier are managed.