Hello,
We are seeing a stability issue with the AD8338 VGA and would appreciate some guidance.
We are trying to amplify a ~500kHz signal from an antenna, the following is the circuit we are using:
(output is loaded by 2x470Ω resistors, oscillation persists even with no output load)
When gain is increased above ~50 dB, the output begins to oscillate at ~1–2 MHz. The input signal contains broadband noise, and it appears that noise peaks can momentarily overdrive the AD8338, after which the oscillation starts.
Could this behavior be related to the “Overdrive Recovery vs. Time” characteristic shown in the datasheet?
Are there recommended techniques to improve stability under brief overdrive conditions?
We can provide measurements or scope captures if needed.
Thank you!