about the vco

I would advise you to purchase a COTS VCO instead as the performance is better than your design. There are too many consideration when designing VCO including phase noise, pushing and pulling figure, tuning frequency range, etc....

Zcomm and VariL are 2 VCO manufacturers.

But my boss let me to desing with myself

Personal opinion and experience:

If you don't need anything special ( i.e. noise, output level, frequency, etc ) try to buy it ready and don't waste time !
You will see that your project will have always something wrong very appreciated from your enemies.
You can use the saved time trying to impruve the other parts of the project.

At the end : if anything is available on the market ( and of course if it fullfils your requirements ) it will cost for sure less than to reinvent it !

As reference: inside the mobile phones the VCO and some other building blocks are bought instead than developed, even at numbers more than 10.000 pieces sold.

Mandi

A very wise advice. Go for the commercial VCO.

PS about the phones, even when they are sold with the tens of millions, the VCO is always bought.

Cheaper, better, faster, easier, and most of all: controllable.

Bert

If you want low noise select Si technology, for the frequency of your interest a BJT is good, select one with a transition frequency above 2 times the max output tune ( 9GHz process would be good ).

Look at this and replace tank circuit for wide range tuning . BUT , LOOK carefully at comments inside of this APNOTe , they wrote u cannot use this schematic solution for mass production because tank tolerances.

http://www.infineon.com/cgi/ecrm.dll...rent_oid=13803

As well go to www.alphaind.com at the varicap section APPNotes - a lot of material.