need help to design digital to analog converter using binary weighted capacitor circuit ??
cant find it anywhere

 

Most DACs use resistor trees. Rajsheck, can you post a description or a schematic of how capacitors would work instead?

 

There is some talk online, but you would need an IEEE membership to see the articles. R/2R ladders work really well.

 

You could download some ADC datasheets to get ideas.

National's ADC0820 is one that uses sampling caps with comparators.
Dallas/Maxim's MAX1300/MAX1301 is another series.

Crystal Semiconductor's CS5012/CS5014/CS5016-KPxx is another.

 

Something here, it's a google cache as the link is down.

 

the solution to the question can be found in the book
"CMOS Analog ckt. Design " by Allen & Holberg