Hello

I have designed an inverting circuit with a power OpAmp from Apex Microtechnology - PA09 which has high slew rate of 200V/µs. I have used their evaluation kit and made all the leads small, bypassed the supplies and have good ground plane. However when I operate the OpAmp with a minimum power supply of +12V and -12V(according to datasheet) and give a ground input, the output oscillates with a waveform similar to sinusoidal with 14Vp-p @2.2MHz. Does anyone know what is the reason for this oscillation.?
Thanks

(I have attached my circuit diagram)

 

Hello

I have designed an inverting circuit with a power OpAmp from Apex Microtechnology - PA09 which has high slew rate of 200V/µs. I have used their evaluation kit and made all the leads small, bypassed the supplies and have good ground plane. However when I operate the OpAmp with a minimum power supply of +12V and -12V(according to datasheet) and give a ground input, the output oscillates with a waveform similar to sinusoidal with 14Vp-p @2.2MHz. Does anyone know what is the reason for this oscillation.?
Thanks

(I have attached my circuit diagram)

Is your "ground" a real ground or is it from the R6 and R7 voltage divider?

If it is from a pair of resistors, then you need to make that virtual ground "stiffer" with lower value resistors.

Also, if you don't need all of the extremely high slew rate, you can increase the 4.7 pF cap to something larger - keep trying up to 100 pF (higher values will give slower slew rate).

 

Post a picture of the circuit layout.

 

Also, if you don't need all of the extremely high slew rate,

Strong point there. What bandwidth do you need?
That thing is oscillating at 96 V/us
With that 200 V/us specification, you can output .636MHz@20Vp-p
Is that what you need?