How do I view the dynamic resistance Q2 in ltspice?

 

Hi 999,
Please post your LTS asc file example.
E

 

The file is not loading for some reason.

 

The file is not loading for some reason.

hi 999,
It should load OK, as a name.asc file

Try again.
E

 

Please

 

How do I view the dynamic resistance Q2 in ltspice?

Hi. Your scheme is very bad. It's also very skewed. The upper transistor is in saturation mode. If you rearrange R1 and R2, you will improve the situation somewhat. Once 45 years ago, I also tried to turn on PNP and NPN transistors on the other side, but nothing worked out for me. The slightest change in the resistors changed the voltage on the collectors very much! My goal of getting half the food was never achieved. It is a bad idea to turn on current sources in series (counter). And the dynamic resistance is easily determined. In low-signal AC mode, you supply a 1 Amp AC power source to the desired node.
See

 

I didn't quite understand how to do it?

 

hi 999,
Is this what you are asking?
E

 

I don't know yet, am I confused by the 1K resistance, is it very small?

 

See post #6.

 

Oh yes, thank you, can I have the source code?

 

I'm getting something incomprehensible.

 

hi 999
Bordodynov's plot is showing Output impedance of your circuit, of approx 3.7k

E

 

At 10kHz 140K

 

hi 999,
Using his circuit, yes 140k. at 10kHz.
Note his strange value of R3... ?
If you use R3 =1K I get this.
E

 

Yes, it's strange!?

 

Do you distinguish between the gain mode and saturation mode of the transistor? I understand you haven't sorted out my information. I switched the circuit using a strange value of the resistor to gain mode. In reality, it is difficult. The slightest change in magnitude greatly changes the voltage at the collector point.

 

At 1K, the transistor Q2 is in saturation and the collector potential does not change, so the dynamic resistance of 3,7K?

 

Yes, you can see that at 1kOhm there is no gain in your signal. I emphasize once again - the electrical circuit is bad, redo it.

 

No matter how I set it up, it will not work well, do I still need direct current feedback from the collector to the base?