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ADA4922-1 Offset voltage and Output Load

Question asked by kashef85 on Aug 20, 2015
Latest reply on Aug 27, 2015 by kashef85

Hi

 

I am using ADA4922-1 to convert a single ended square wave of 1 KHz frequency from single ended to differential. The input square wave have an arbitrary DC offset. In order to remove the DC offset i am using a high pass filter between signal source and input of ADA4922-1. The high pass filter is a capacitor of 1uf in series and a resistor of 300K in parallel. The problem is that ADA4922-1 itself is introducing an offset of about 0.3V at the input. Even when there is no input signal, 0.3V apear at the input port while the output of ADA4922-1 is correspondingly at +/-0.3V.

 

Supply voltage is +/- 12V with 100 nF coupling capacitor. Both outputs have an RC low pass filter R=41 ohms, C=3.9 nF. The output drives an ADC with input impedance of 1 Gohms

 

Please suggest a solution to remove this DC offset. Also suggest should i add a load resistor as the ADC impedance is very high?

 

Thankyou & Regards

Kashef

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