Offset problems with AD8054

       Hi. I have the above scheme using the AD8054 op amp. If I ground the JP2 pins I have 0.15 V at the 1, 2 and 3 pins. When I raised pin 3 in the air and connected it directly to GND I still had 0.15V at 1 and 2 pins. If it is not clear in the picture, 2 and 3 pins are inputs and 1 is output. Supply is +/- 5V. What ever voltage there is at JP2 pins there is always an 0.15V extra voltage at the output. Could anyone please help me? Thank you.

Parents
  •         Thank you very much for your quick response. I hope this is a better picture. As I said in my first post, I have a constant offset of 0.15V. Before the +input there is a voltage divider of 1/8. The op amp is connected as a repeater with a negative reaction. Instead of having at the output the voltage divided by 8 I have the voltage divided by 8 plus 0.15V. I must mention that the voltage to be divided is applied between R34 and R38 ,and R37 is taken out of the board. If there is no input applied, there is still 0.15V at 1,2 and 3 pins. When I raised pin 3 in the air and connected it directly to GND I still had 0.15V at 1 and 2 pins. I also tested the op amp off circuit, I connected pins 1 and 2 togheter and I applied 1.45V at pin3. At output I had 0.7V or 2.45 V, and never 1.45.

    Thank you very much.

Reply
  •         Thank you very much for your quick response. I hope this is a better picture. As I said in my first post, I have a constant offset of 0.15V. Before the +input there is a voltage divider of 1/8. The op amp is connected as a repeater with a negative reaction. Instead of having at the output the voltage divided by 8 I have the voltage divided by 8 plus 0.15V. I must mention that the voltage to be divided is applied between R34 and R38 ,and R37 is taken out of the board. If there is no input applied, there is still 0.15V at 1,2 and 3 pins. When I raised pin 3 in the air and connected it directly to GND I still had 0.15V at 1 and 2 pins. I also tested the op amp off circuit, I connected pins 1 and 2 togheter and I applied 1.45V at pin3. At output I had 0.7V or 2.45 V, and never 1.45.

    Thank you very much.

Children
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