Transition from lumped comp. to disrtubed comp. (LNA)

Why u want in this LOW frequency work with disrtubed elements!?
F=1G
λ=0.3m

David

what do u mean by wavelength = 0.3m .. wat 2 do with that ?


because its my final year project in the univerisity so that is my supervisor's requirments..

I think the question is: Do you need to physically build this circuit and test it, or just simulate it on an analysis program?

If you have to build it, you will find that some of the transmission lines may be quite large (as large a λ/4, or ~0.1 meters).

You may not be able to directly convert your existing lumped element circuit, component by component, into a distributed one. There might be a better different topology to use for a distributed circuit.

In general, series lumped element inductors can be approximated by high impedance transmission line sections, and shunt lumped capacitors can be approximated by low impedance transmission line sections.

If you have a wide bandwidth requirement, it will be harder to do--keep the transmission line sections small. If it is a single frequency, it is easier to do and you can use long length transmission line sections.

Rich

www.MaguffinMicrowave.com

The biff
that exactly I mean!

Yep, just explaining what you meant.

Don't forget, some students are still learning which end of the soldering iron gets hot!

thank you for ur replay DDavid and biff44,,

ya i do need to simulate build and test ...using the microstrip ,, that's y , i want to use the disrtibuted components ..

the bandwidth is 90 Mhz,,

in my lumped components circuit ,,i designed it using the ATF-34143 with 2 inductors for the simultanoues input matching impedance (ZM1) and simultanoues output matching impedance
also in each side i added the component( TLIN ) for defining the angle 90 degree and impdeance. etc..

if u didnt get my point i'll print scrn for the circuit diagram .. help me plz i dunno how to start with this type of circuit

A print will help to understand better.

As it seems that for you the matching is done with lumped elements, the line to connect them has to add the lowest possible influence.

So the way to design this is introducing these effects in your schematic trying to minimize phisical lenght of TLs, or, as it is done usually, make a mixed design with lumped & TLs, for example, if you need a source degeneration of less than 1nH, you can design it with a small TL to gnd.

I hope it can help.

Mazz