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楼主 |
发表于 2015-10-30 09:37:32
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回复 3#&4#
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% successive approximation converter %
% with finite DAC's slew-rate and bandwidth. %
% Case of binary weighted resistive array DAC %
% code by Fabrizio Conso, university of pavia, student %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function counter=kelvin(input,nbit,f_bw,sr,f_s,v)
% input = input sample
% nbit = bits of the converter
% f_bw = DAC bandwidth [f_s]
% sr = DAC slew-rate [V_fs/T_s]
% f_s = normalized sampling frequency
% v = thresholds array
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% global variables %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
%threshold_id=v(12); %initializing ideal threshold to 0.5
threshold_id=v(nbit);
counter=0;
in=input;
threshold(1)=0.5;
tau=1/(2*pi*f_bw); %DAC的时间
Tmax=1/(f_s*nbit); %完成一次比较所需的最少时间
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
for k=1:nbit
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% skip of last subtraction
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
if k < 3
%if k<6
Tmax=2*Tmax;
end
if k==nbit
if (in-threshold_id) > 0
bit=1;
else
bit=0;
end
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% finite bandwidth & slew-rate %
% error calculation %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
else
deltaV=abs(threshold_id-threshold(k));
slope=deltaV/tau;
if slope > sr
tslew=(deltaV/sr) - tau;
if tslew >= Tmax % only slewing
error = deltaV - sr*Tmax;
else
texp = Tmax - tslew;
error = (deltaV-sr*tslew)*exp(-texp/tau);
end
else
% only exponential settling
texp = Tmax;
error = deltaV*exp(-texp/tau);
end
%threshold(k+1)=threshold_id-sign(threshold_id-threshold(k))*error;
threshold(k+1)=threshold_id-sign(threshold(k)-threshold_id)*error;
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% successive approximation %
% conversion algorythm %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
%if (in-threshold(k+1)) > 0
if (in-threshold(k+1)) > 0
threshold_id=threshold_id+v(nbit-k);
%threshold_id=threshold_id+v(nbit-k);
bit=1;
else
threshold_id=threshold_id-v(nbit-k);
%threshold_id=threshold_id-v(nbit-k);
bit=0;
end
end
Tmax=1/(f_s*nbit);
counter=(counter+bit*2^(nbit-k));
%counter=(counter+bit*0.5^(nbit-k+1));
end
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Output %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
counter=counter;
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
sorry 我忘记把代码贴上来了=。=大神们再看看~ |
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