ADA4817 oscillation problem

Hi,

I am using ADA4817_1 in my circuit as low noise amplifier. I am using SOIC package. In my PCB I am using it as DIP so I have used SOIC to DIP adapter. The SOIC package has metal under its body. On my adapter there is metal in the middle line of the array of total 8 pins. Now if I solder opamp chip directly on the adapter there is a chance that all pins get shorted through metal connection. So we had put a tape in the gap between the body of SOIC chip and the adapter. I am experiencing oscillation of 20 MHz from my circuit of amplitude 10 mV. I am expecting it is coming from the opamp. Is there any way to get rid of the oscillation? Is there any mistake in the process I tried to avoid metal short as I described before. I followed power supply by passing technique in my circuit.

Thanks.

Niloy.

Parents
  • Niloy,

      I don't like to use the word "never", but I'm tempted to say you will never get your circuit working.

    If you have nanohenries of inductance in your supply leads and 2-5pF of stray capacitance everywhere,

    and 1k-10k resistors, I can believe you will get 20-200 MHz oscillations.

    Schematic?

    Highest signal frequency?


    Depending on gain and frequency, you could try ADA4897-1, ADA4805-1, or ADA4084-1.

    Otherwise, you will have to do  a prototype board and solder the part directly down to the board.

    Harry

Reply
  • Niloy,

      I don't like to use the word "never", but I'm tempted to say you will never get your circuit working.

    If you have nanohenries of inductance in your supply leads and 2-5pF of stray capacitance everywhere,

    and 1k-10k resistors, I can believe you will get 20-200 MHz oscillations.

    Schematic?

    Highest signal frequency?


    Depending on gain and frequency, you could try ADA4897-1, ADA4805-1, or ADA4084-1.

    Otherwise, you will have to do  a prototype board and solder the part directly down to the board.

    Harry

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