Need help to plot frequency response of transconductance of BJT with LTSpice

[ATMega]

Great, thank you so much ronsimpson

 

[ATMega]

ronsimpson the problem is when I want to have the frequency response of Gm, it's flat!

 

[ATMega]

ronsimpson the problem is when I want to have the frequency response of Gm, it's flat!

 

[ronsimpson]

With the 2N2222 transistors the circuit is set up to bias right.
With you "X" transistors; With no input voltage (B1=B2=2volts) the collectors are near 2V or near 11V. Not good. I moved the Collector resistors to Emitter resistors so the output voltage is near 6 volts. (the amplifier needs to have room to move up and down, Vout needs to be near the center of the supply voltage) I had to play with the value of the Emitter resistors to get that to happen.

I don't really understand the amplifier. It is not a real world amplifier. It is a text book amp. It needs feedback to make it stable.
"don't worry about the base current"
apparently we also don't need to think about biasing the amplifier, etc. Temperature stability?

I probably an leading you down a bad path. I want the thing to work so I can study it. It can't work with the collector and emitter current being the same.
I think this is an exercise in math so your teacher wants a bandwidth number from a formula. So you know the collector current and you can find out the capacitance of the transistor and that will get you a bandwidth. I should stop helping/hindering you. In my world I would use this as a piece of a amplifier not as a amp. I have to really make it work (over a wide temperature range, with supply voltage changes, tolerances of parts, etc) The teacher would not want to see me in class.

I think last week you were give a formula for bandwidth, use it and be done.
Sorry I took you away from where the teacher wants you to go.

 

[ATMega]

Your help is really instructive. thanks a lot!