transfer function in small signal mosfet model

Sure can. However I won't. If you can't do loop and nodal analysis you should choose another trade.

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

See....

Newsgroups: alt.binaries.schematics.electronic Subject: transfer function in small signal mosfet model (from S.E.D) - TransferFunctionSED.pdf Message-ID:

...Jim Thompson

thank you very much Jim! I used nodal analysis as you suggested and I got an enormous transfer function! Hope it's right.. do you know about some good book about the project of analog radio frequency amplifiers where I can find examples and theory?

thanks again and sorry for my english

I wouldn't expect an "enormous transfer function". Post your work.

...Jim Thompson

Il Thu, 12 Apr 2007 09:44:33 -0700, Jim Thompson ha scritto:

here is my work ..hope it's allright! but I don't think so :P

I notice that you morphed Rd into Ro at the beginning of all the algebra; I'll stick with Rd.

There is more than one kind of transfer function, such as the short circuit transfer admittance and the open circuit transfer impedance, etc., but I assume that what you want is the voltage transfer ratio.

The numerator is:

-gm Rd + Rd Cgd s

The denominator is:

( Cds ( Cgd + Cgs ) - Cgd ( 2 Cgd + Cgs )) Rd Rs s^2

• ( Cds Rd + Cgs Rs + Cgd ( Rs - Rd + gm Rd Rs )) s + 1

One of us made a mistake in the algebra! :-(

And I dropped an "S" in my first page start :-(

...Jim Thompson

Il Thu, 12 Apr 2007 14:19:30 -0700, The Phantom ha scritto:

can you check your denominator? because mine is:

( Cds ( Cgd + Cgs ) + Cgd Cgs ) Rd Rs s^2

• ( Cds Rd + Cgs Rs + Cgd ( Rs - Rd + gm Rd Rs )) s
• 1

thanks! ;)

I carefully checked and found that I had made a single sign error. I agree with your result with the exception of a single sign, which I have indicated.

I get a plus sign here: ...Rs + Rd...

I carefully checked again and I get a plus sign too! thank you very much for the help!

matteo