May I know what is the name and function of the component in the red circle?

 

It looks like a buffer to me.

 

It looks like a buffer to me.

May I know the output to the DUT pin is an analog or digital signal?

 

The max19001 is not in production. It is old and has been replaced.

The symbol is an amplifier or buffer. There are many inputs that control its function.
If this was an audio amplifier (it is not) the lines at the top would be called Base, Mid, Treble, Loudness, Volume, Mute.

RonS.

 

The max19001 is not in production. It is old and has been replaced.

The symbol is an amplifier or buffer. There are many inputs that control its function.
If this was an audio amplifier (it is not) the lines at the top would be called Base, Mid, Treble, Loudness, Volume, Mute.

RonS.

may I know the DAC output is an analog signal to the end of the buffer is analog signal or digital signal?

 

All digital signals are analog.
Have you read the MAX19001 datasheet?

 

All digital signals are analog.
Have you read the MAX19001 datasheet?

I have read the datasheet any the statement state that All digital signals are analog.

 

This IC drives a long wire. COAX At high frequencies "long wire" might be short in cm or inches. The output is analog driving digital. At the far end of the wire we want a square wave. The wire adds distortion. So the amplifier adds distortion to compensate. It even compensates for cable loss by adjusting gain. It takes linear to make this distortion.

I have not used this part and don't understand all, but it looks like the goal is to make "digital" by using analog.