Photodiode Tansimpedance amplifier Oscillations at Output

[emranshd]

Hi! i am working on the design of photodiode transimpedance amplifier of 100MHz bandwidth using OPA657 Opamp. The first time when i switched on the power to the circuit, there were high frequency sinusoidal oscillations of about 10Vp-p. These Oscillations were removed after i tuned the feedback capacitor to 1pF. But the problem is that oscillations of 100 mV p-p having frequencies from 100 MHz to 400 MHz still remain there. These oscillations occur at the I/O pins and Supply pins of opamp. What could be the cause of these oscillations and How can i remove these oscillation when tuning the feedback capacitor and resistor has no effect in removing these oscillations.

 

[ronsimpson]

Need more information! Send schematic. Need picture of layout, part plaacement.

 

[crutschow]

You've learned one of the first rules of high frequency amplifier design. It's very easy to build an oscillator when your intention was to build a high frequency amplifier.

Layout and decoupling including a ground plane of a 100MHz amp is critical to prevent oscillations. We can't help you without seeing the circuit schematic and the physical layout.