SparkingDog
Newbie level 6
I am stumped. I have an VFA (OPA355) ckt configued with gain=+2. Rf=499ohms, Vs=+/-2.5V. I have done everything I can think of to minimize stray capacitance. The amp has good decoupling.
The amp is currently unloaded.
The Problem:
When I apply a 0.5V, 10Mhz square wave to the input, the output has a large overshoot (more than 50%); but only on the falling edge. What could cause this asymmetry?
As an experiment I changed the gain to +1. With a 499 ohm feedback resistor the overshoot remains but it disappears if I short across Rf. A 2pf Cap across Rf reduces the overshoot by half.
The amp is currently unloaded.
The Problem:
When I apply a 0.5V, 10Mhz square wave to the input, the output has a large overshoot (more than 50%); but only on the falling edge. What could cause this asymmetry?
As an experiment I changed the gain to +1. With a 499 ohm feedback resistor the overshoot remains but it disappears if I short across Rf. A 2pf Cap across Rf reduces the overshoot by half.