Hi,
I'm trying to build a 2-200 MHz isolation amplifier.
For 13 dBm I need abt. 120 mA peak current, 70 mA quiescent.
The circuit is a voltage to current converter, followed by a double cascode.
2N3904 is too slow, BFQ19S is too hot, it would do 1 GHz, but brings me negative input impedance, gain peaks and so on. I'm playing with the usual ferrite beads, but that does not bring complete relief.The emitter node of the v/i converter definitely wants to play a capacitively loaded follower. I'm just making GND cutouts in the layers under the emitter.
Is there a transistor abt. halfway in speed? BFU590 etc is even faster. Something flat like SOT-89 would be fine. And I would not object 1 GHz BW if it comes without the side effects. :-)
Any ideas?
Cheers, Gerhard