BrunoARG
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None transistor has so large Band-width so that you reach 10 MHz without loosing gain. You need negative feedback to enlarge Band-Width but still maintain gain=10 which is pretty affordable.
Did you thought of OP amps or you can not use them because of design constraints ?
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For those in your simulation with Av=5 and BW=? (cutoff frequency is not the BW...)
What you have said , of course is necessary.I know gain will decrease proportionally with the frequency at a point, and as current gain will vary with temperature and other factors I have to use the negative feedback, as far as I know my circuit has, indeed.
That usually requires more than one transistor, but it is then possible to keep the gain fairly flat up to some usefully high frequency.
What you end up needing depends on the required gain, the maximum frequency, the output voltage swing, the type of load being driven, and the available supply voltage.
It may be a lot easier to use a suitable op amp than a bunch of discrete transistors.
You can now buy MMICs (monolithic microwave integrated circuits) with essentially fairly flat gain from dc to 6 Ghz. That may not be what you need, but there are a lot of ICs out there that can do some pretty amazing things.
one can also use CMOS IC's with negative feedback with linear gain open loop of 1000 for buffered inverters.
I've used these in the early 70's for many non-critical 10MHz linear applications.
Now you can choose faster IC's in 5V logic with 50 ohm internal RdsOn or use discrete MOSFETs.
https://www.fairchildsemi.com/application-notes/AN/AN-88.pdf
Certainly better than a single transistor amplifier.Tony, so you say that if I build that discrete op amp I would get better frequency response?
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