Capacitor mismatch modeling in matlab

[je01911]

Hi.

Before start to design the SAR ADC, i want to simulate the relationship between capacitor mismatches of CDAC and SAR ADC using matlab.

when capacitor mismatch ratio is 'sigma' and Cu is unit capacitance,

plz check the equation and next matlab code

capacitor mismatch ratio ~ N(0,sigma^2)

when i want to make the capacitors with mismatch using matlab

for i = 1 : bit

    C(i) = 0; //reset the variable before declare i th capacitance (1 = MSB, bit = LSB)

    for j = 1 : 2^(bit-i)

        C(i) = C(i) + Cu + sigma*randn(); //make and sum the unit capacitors with mismatch

    end


end

C(bit+1) = Cu + sigma*randn() //LSB capacitor

There are some papers about maximum ENOB and mismatch ratio.

However i cant plot the relationship between them like papers.

So, i cant be sure about my matlabe code

please check the equation and code