- #1
Aryia
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- TL;DR
- Trying to amplify a -6 dBm 75MHz signal but encountering amplifier stability issues
Hello all,
I'm currently trying to amplify a -6 dBm 75MHz signal to at least 31 dBm by using THS3491 evaluation boards. The boards came with an attenuation circuit which I have removed, currently there is only a 50 ohm resistor in series with the output (output-6 dBm). Initially our approach was to tweak the gain by changing the feedback resistors RF/RG but the amplifier seems to become unstable at a gain over 10. Is this normal behavior?
Our second approach was to use two gain amplifiers in series (one 8x with no output resistor into a 10x with a 50 ohm resistor). We received somewhat promising results. We expected 26 dBm output but only measured 23 dBm and the oscilloscope sine wave reading has an irregular shape. *Hopefully I can attach some images*.
I have limited experience with amplifiers, am i approaching the issue wrong?
I'm currently trying to amplify a -6 dBm 75MHz signal to at least 31 dBm by using THS3491 evaluation boards. The boards came with an attenuation circuit which I have removed, currently there is only a 50 ohm resistor in series with the output (output-6 dBm). Initially our approach was to tweak the gain by changing the feedback resistors RF/RG but the amplifier seems to become unstable at a gain over 10. Is this normal behavior?
Our second approach was to use two gain amplifiers in series (one 8x with no output resistor into a 10x with a 50 ohm resistor). We received somewhat promising results. We expected 26 dBm output but only measured 23 dBm and the oscilloscope sine wave reading has an irregular shape. *Hopefully I can attach some images*.
I have limited experience with amplifiers, am i approaching the issue wrong?