Anyone konw this circuit in the attachment?

[icsoul]

What kink of circuit it is ?

How to analysis its transfer function?


I want to get some stuff for this circuit.

Thanks !~

 

[icsoul]

Nobody knows?

 

[jfyan]

Nobody knows?

hi,
it looks like a broadband amplifier using capacitive degeneration.
jeff

 

[Alex_IC]

Taking into account first order effects only the transfer function is
v(outn)/v(inp)=Gm*Routn, v(outp)/v(inp=Gm*Routp, here Gm=(1+sRC)/R

 

[n1cm0c]

A similar circuit is commonly used to remove the long tail in gaseous detectors for high energy particles. It's called a shaper there, or tail cancellation amplifier.

There's a description of such a circuit in here ,
http://dx.doi.org/10.1016/j.nima.2006.02.168
and the concept is explained here
**broken link removed**
a chip implementing this appears here,
**broken link removed**
look for the shaper section.

hope this helps.

 

[hunk]

used to extend bandwidth of gm

 

[icsoul]

Taking into account first order effects only the transfer function is
v(outn)/v(inp)=Gm*Routn, v(outp)/v(inp=Gm*Routp, here Gm=(1+sRC)/R

Alex_IC:

Could you explain how to get this transfer function?

Added after 5 minutes:

A similar circuit is commonly used to remove the long tail in gaseous detectors for high energy particles. It's called a shaper there, or tail cancellation amplifier.

There's a description of such a circuit in here ,
http://dx.doi.org/10.1016/j.nima.2006.02.168
and the concept is explained here
**broken link removed**
a chip implementing this appears here,
**broken link removed**
look for the shaper section.

hope this helps.

I can not access the first URL.
This circuit is used to compensate high frequency loss.
Now I want to know is that what's the operation principle, how to analysis, and what's the type(name) of this circuit?

Whatever, thank you very much!~

Added after 5 minutes:

used to extend bandwidth of gm

hi, hunk

Could you explain this in more detail?

Thanks!~

 

[Alex_IC]

We can assume that gm>>1/(2*R), so that at low freq (where Cap is negligible) the effective transcondactance of the DiffAmp is Gm=1/R. At high freq the Cap shunts the R, and effective transcondactance is Gm=1/(gm+gm).

So more accurate eqation is

v(out)/v(inp)=(Rout/R)*[(1+RCs)/(1+gmCs)]

 

[icsoul]

We can assume that gm>>1/(2*R), so that at low freq (where Cap is negligible) the effective transcondactance of the DiffAmp is Gm=1/R. At high freq the Cap shunts the R, and effective transcondactance is Gm=1/(gm+gm).

So more accurate eqation is

v(out)/v(inp)=(Rout/R)*[(1+RCs)/(1+gmCs)]

Thank you, Alex_IC!

It is very helpful!~

 

[cdz]

This circuit is called amplify with high freauency boost.

 

[Jim cage]

This circuit also has the advantage of degenration without an IR drop and having more headroom. The disadvantage is that it has higher noise due to current sources noises which are not common so the noise is uncorrelated at the Gm's output. The circuit is used to have broadband amplification where at high frequency the capacitive load dominates the output impedance and so the Gm will get higher to have the same gain.

 

[icsoul]

This circuit is called amplify with high freauency boost.

Hi,cdz

Do you have some good stuff about this?

Added after 2 minutes:

This circuit also has the advantage of degenration without an IR drop and having more headroom. The disadvantage is that it has higher noise due to current sources noises which are not common so the noise is uncorrelated at the Gm's output. The circuit is used to have broadband amplification where at high frequency the capacitive load dominates the output impedance and so the Gm will get higher to have the same gain.

Hi, Jim cage

Could you recommend some material about this topic?