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ADA4870 - composite amplifier

Question asked by chickenek69@gmail.com on May 21, 2016
Latest reply on May 24, 2016 by JinoL


Hi,

 

I am trying to make a project based od ADA4870 figured as unity gain current buffer. Looking on it's 23th page of datasheet i found it connected with composite amplifier and i have some questions now:

1. Is the ADA4637-1 absolutely best amplifier in Analog Device catalogue in term of small value analog signal parameters (error, noise, etc. in aplication like DAC output stage). If not what else should I look at?

2. Refering to the 23th page of ADA4870 datasheet if i understand correct resistors 1k + 110R sets the gain? ADA4637 is stable at gain more than 5, so can i change those resistors to 1k2 + 200R to set ADA4637 at gain = 6 without further troubles?

3. Same page of datasheet as above - is the capacitor connected pararell with 1k resistor needed to achieve stability? I need only audible frequency response, but i am not sure if it will be fully stable without this capacitor (i guess yes, but it's better to ask anyway).

4. Last one - in such a configuration can i bias output stage of ADA4870 (mean connecting output also to a V- via resistor to make output stage active all the time) as i did with "alone" operational amplifiers, without risk of damage ADA4870 or ADA4637? (again i guess yes)

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