I have been looking at the AD7760 data sheet and at the AD7760 discussions here and I've got two questions about the fully differential amp:
1. I build an instrument with a differential input. That input may be used with single ended signals at either leg or with a fully differential signal -- I have no control over that. I do understand that the AD7760 front end pins (Vin- and Vin+) need a symmetrical (Vin- = - Vin+) differential input. A fully differential OpAmp is a good choice to convert a maybe-single-ended-maybe-differential signal into an always-differential signal.
Do I understand correctly that I can NOT use the AD7760 internal fully differential amp for that purpose? It seems to require a differential signal at the amp's input. I would therefore need another (external) differential amp for signal conditioning.
2. Does the AD7760 internal differential amp need to be configured exactly as shown in the data sheet? It is advisable to configure it e.g. as a 2nd order fully differential MFB lowpass?
Thank you for your help!