Charge distribution AD Converter

[snoop835]

Hi Guys,

I am designing 8-bit SAR Converter based on the following journal. (see attachment file)

Can someone throw me some light on how to decide the capacitor value for the sample-hold circuit. Is there any good reference or design guidelines for this circuit?

Cheers!

 

[feier0251]

the value of the capactor can be several pf,you should simulate your circuit.
and you also consider the parasitic capactor .

regards

 

[sunking]

the main problem is KT/C noise.
pay attention to it not bigger than 1/3 of least bits

 

[willyboy19]

For a mere 8-bit ADC, kT/C noise should not be an issue. You should pick it based on matching. As a second thought, even matching should not be an issue here since it is again, an 8-bit converter.

 

[telleric]

several pf is enough for you to realize a 8bit resolution. I think the key are the cap mismatch and the offset of your comparator.

 

[mengyj0706]

i want to design a 10bit 50khz low power sar adc,can anyone give me some advice or reference ?

 

[piao]

you can refer to the book from DAvid Johns & ken Martin. it was discussing the charge distribution ADC.