need help on topology of LNA

[tieuquaybk]

hi all !
can somebody tell me how to make connection between components on microwave frequency ? as i see ,it use microstrip too . But still have some dout on it . And if we use the microstrip ,then its lenght and width are choosen by which standard ? and how it affect on circuit matching

 

[springf2000]

that is easy, use the APPCAD of the agilent to compute it , APPCAD is free software, 50 ohm is ok, good luck

 

[tieuquaybk]

when thickness of subtrate and dielectric constant were given , then characteristic impedance depend on the width of microstrip ... but as you see ,widths of those line in this application are not the same . How should we understand about that?
thank for helping

 

[estradasphere]

You can find exactly the same layout in the technical data of Freescale MBC13900 (see attachment). As you see all RF lines have such a width that Z0 is 50 ohm. R2 (refer to attachment) is for biasing, the line width is not 50 ohm. L1, R4, L2, R1 and R5
have all transmission lines of 50 ohm.

Moreover, i would use cpw (coplanar) instead of microstrip.

hope this helps.

 

[tieuquaybk]

oh .. maybe i figured out somethings
characteristic impedance of transmission line is 50 , accept for microstrip that connect to V.supply this microstrip need i higher impedance (about 100 Ohm ) for stability
... but still now i don'n know the affect of microstip's length on curcuit matching . Which length is required ? can somebody help me.

 

[a_ronagh]

Please refer to the following book, it is a very useful book for designing LNAs and microstrip matching networks:
"Microwave Transistor Amplifier Analysis and Design" by Guillermo Gonzalez ,PRENTICE HALL,1996

 

[tieuquaybk]

i've known that's a good book (i've read chappter 10 ) but can't find the whole book .