Ideas/design about active biasing for ATF36077

[abdoeng]

ads user help me

i have serious problem wih ATF36077 ,condition of bias vds=1.5,ids=10 ma,
vgs=-.2,how??????,i obtain the vol of vgs,it was so small,also any buddy give me the wquastions of calculation of rs and rd
thanks so much

 

[Mazz]

Re: ads user help me

Have a look at hxxp://www.applet.cz/~ulcak/lna.htm. (replace xx -> tt)
Bye
Mazz

 

[abdoeng]

Re: ads user help me

hi mazz thanks for reply but i see tha site bofore if u have any paper about supply of atf36077 i will be thanked,how i get vgs=-.2 are u see it is impractical

 

[boy]

Re: ads user help me

if you realy need that value (very seriously), you may use 16bit D/A.

 

[radiohead]

Re: ads user help me

Use an active biasing scheme, it will fix the drain current and adapt the VGS to it's purpose!

 

[abdoeng]

Re: ads user help me

any buddy have that design or ideas about biasing pls upload it or reply me at pm
regards

 

[boy]

Re: ads user help me

There is an IC from infineon for an active bias circuit.
https://www.infineon.com/cgi/ecrm.dll/ecrm/scripts/prod_ov.jsp?oid=13786
i am not sure that you can use -0.2 v or not.

 

[toonafishy]

Re: ads user help me

Put a 20 ohm resistor in series with the source lead to ground, DC ground the gate with an inductor, put 1.7 volts on the drain. Assuming a drain current of 10mA, the SOURCE to GROUND voltage is 0.2 volts AND thus the voltage from GATE to SOURCE is -0.2V (since the gate is grounded). The DRAIN to SOURCE voltage will be 1.5V (1.7V - 0.2V). Try it.

Check this out, too:

h**p://www.applet.cz/~ulcak/lna.htm

 

[abdoeng]

Re: ads user help me

hi i avoid connect source to bias,here my design ,is that design correct,i apporximate that drain current equal source cuurent and gate ground voltage=-.2 plus voltage drop on source resistance