What happen to output transistor?

[bruces3]

This is the output from collector.
The input is pulse.
When pulse is from low to high , output is likely to respon quick.
But when pulse is from high to low , output is about to have slow respon.
Why does the transistor is likely to off slow not like when on?

 

[khongai]

its real chracteristic of transistor

 

[yego]

You obviously haven't provided info on the circuit your transistor sits in ( which would certainly help ), the frequency, voltage, current, the type of your transistor.... etc.
The on and off times may differ due to technological assymetries, quantum effects and mobility of majority charges. Of course this is not the case here as those values shouldn't differ by more than at most half order of magnitude.
In your case it is quite likely that there is some kind of integrating circuit either on the input or output of your transistor.
I'd rather not suspect the transistor itself because the shape of the falling slope suggests integration, and there are no big capacitances inside the planar structure of the transistor to cause such an effect.
Check your circuit and give more details.
regards, yego

 

[tkbits]

When a transistor is turning off, it acts somewhat like a capacitor. That's why there's a second transistor on the outputs of digital ICs. One transistor is used to create a sharp edge in one direction, the second transistor creates a sharp edge in the other.

 

[echo47]

Please show us you schematic, and tell us the waveform's frequency and amplitude.

 

[Badaruddin]

You have to inform schematic diagram, input signal and frequency.