关于maxim测ADC dnl，inl的程序的一问

%Code density/histofgram test to calculate INL and DNL require a large number of samples.
%Step 1: Apply a close to full-scale sine wave (but not clipping) and find the mid-code for the applied signal.
%Step 2: Apply the same sine wave input, but slightly larger amplitude to clip the ADC slightly.
%Run the following program, enter the number of samples, resolution and mid-code from Step 1and continue.
%Copyright Au/Hofner, Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA94086
%This program is believed to be accurate and reliable. This program may get altered without prior notification.
filename=input('Enter File Name: ');
if isempty(filename)
filename = 'listing';
end
fid=fopen(filename,'r');
numpt=input('Enter Number of Data Points:');
numbit=input ('Enter ADC Resolution:');
mid_code=input('Enter Mid-Code (Mean Code):');
for i=1:13,
fgetl(fid);
end
[v1,count]=fscanf(fid,'%f',[2,numpt]);
fclose(fid);
v1=v1';
code=v1(:,2);
code_count=zeros(1,2^numbit);
for i=1:size(code),
code_count(code(i)+1)=code_count(code(i)+1) + 1;
end
if code_count(1) == 0 | code_count(2^numbit) == 0 | ...
(code_count(1) < code_count(2)) | (code_count(2^numbit-1) > code_count(2^numbit))
disp('ADC not clipping ... Increase sinewave amplitude！');
break;
end
A=max(mid_code,2^numbit-1-mid_code)+0.1;
vin=(0:2^numbit-1)-mid_code;
sin2ramp=1./(pi*sqrt(A^2*ones(size(vin))-vin.*vin));
while sum(code_count(2:2^numbit-1)) < numpt*sum(sin2ramp(2:2^numbit-1))
A=A+0.1;
sin2ramp=1./(pi*sqrt(A^2*ones(size(vin))-vin.*vin));
end
disp('You Have Applied a Sine Wave of (dBFS): ');
Amplitude=A/(2^numbit/2)
figure;
plot([0:2^numbit-1],code_count,[0:2^numbit-1],sin2ramp*numpt);
title('CODE HISTOGRAM - SINE WAVE');
xlabel('DIGITAL OUTPUT CODE');
ylabel('COUNTS');
axis([0 2^numbit-1 0 max(code_count(2),code_count(2^numbit-1))]);
code_countn=code_count(2:2^numbit-1)./(numpt*sin2ramp(2:2^numbit-1));
figure;
plot([1:2^numbit-2],code_countn);
title('CODE HISTOGRAM - NORMALIZED')
xlabel('DIGITAL OUTPUT CODE');
ylabel('NORMALIZED COUNTS');
dnl=code_countn-1;
inl=zeros(size(dnl));
for j=1:size(inl')
inl(j)=sum(dnl(1:j));
end
%End-Point fit INL
%[p,S]=polyfit([1,2^numbit-2],[inl(1),inl(2^numbit-2)],1);
%Best-straight-line fit INL
[p,S]=polyfit([1:2^numbit-2],inl,1);
inl=inl-p(1)*[1:2^numbit-2]-p(2);
disp('End Points Eliminated for DNL and INL Calculations');
figure;
plot([1:2^numbit-2],dnl);
grid on;
title('DIFFERENTIAL NONLINEARITY vs. DIGITAL OUTPUT CODE');
xlabel('DIGITAL OUTPUT CODE');
ylabel('DNL (LSB)');
figure;
plot([1:2^numbit-2],inl);
grid on;
title('INTEGRAL NONLINEARITY vs. DIGITAL OUTPUT CODE');
xlabel('DIGITAL OUTPUT CODE');
ylabel('INL(LSB)');

1. %Code density/histofgram test to calculate INL and DNL require a large number of samples.
   
2. %Step 1: Apply a close to full-scale sine wave (but not clipping) and find the mid-code for the applied signal.
   
3. %Step 2: Apply the same sine wave input, but slightly larger amplitude to clip the ADC slightly.
   
4. %Run the following program, enter the number of samples, resolution and mid-code from Step 1and continue.
   
5. %Copyright Au/Hofner, Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA94086
   
6. %This program is believed to be accurate and reliable. This program may get altered without prior notification.
   
7. 
   
8. filename=input('Enter File Name: ');
   
9. if isempty(filename)
   
10. filename = 'listing';
    
11. end
    
12. fid=fopen(filename,'r');
    
13. numpt=input('Enter Number of Data Points:');
    
14. numbit=input ('Enter ADC Resolution:');
    
15. mid_code=input('Enter Mid-Code (Mean Code):');
    
16. 
    
17. for i=1:13,
    
18. fgetl(fid);
    
19. end
    
20. [v1,count]=fscanf(fid,'%f',[2,numpt]);
    
21. fclose(fid);
    
22. 
    
23. v1=v1';
    
24. code=v1(:,2);
    
25. code_count=zeros(1,2^numbit);
    
26. 
    
27. for i=1:size(code),
    
28. code_count(code(i)+1)=code_count(code(i)+1) + 1;
    
29. end
    
30. 
    
31. if code_count(1) == 0 | code_count(2^numbit) == 0 | ...
    
32. (code_count(1) < code_count(2)) | (code_count(2^numbit-1) > code_count(2^numbit))
    
33. disp('ADC not clipping ... Increase sinewave amplitude！');
    
34. break;
    
35. end
    
36. 
    
37. A=max(mid_code,2^numbit-1-mid_code)+0.1;
    
38. vin=(0:2^numbit-1)-mid_code;
    
39. sin2ramp=1./(pi*sqrt(A^2*ones(size(vin))-vin.*vin));
    
40. 
    
41. while sum(code_count(2:2^numbit-1)) < numpt*sum(sin2ramp(2:2^numbit-1))
    
42. A=A+0.1;
    
43. sin2ramp=1./(pi*sqrt(A^2*ones(size(vin))-vin.*vin));
    
44. end
    
45. 
    
46. disp('You Have Applied a Sine Wave of (dBFS): ');
    
47. Amplitude=A/(2^numbit/2)
    
48. figure;
    
49. plot([0:2^numbit-1],code_count,[0:2^numbit-1],sin2ramp*numpt);
    
50. title('CODE HISTOGRAM - SINE WAVE');
    
51. xlabel('DIGITAL OUTPUT CODE');
    
52. ylabel('COUNTS');
    
53. axis([0 2^numbit-1 0 max(code_count(2),code_count(2^numbit-1))]);
    
54. code_countn=code_count(2:2^numbit-1)./(numpt*sin2ramp(2:2^numbit-1));
    
55. figure;
    
56. plot([1:2^numbit-2],code_countn);
    
57. title('CODE HISTOGRAM - NORMALIZED')
    
58. xlabel('DIGITAL OUTPUT CODE');
    
59. ylabel('NORMALIZED COUNTS');
    
60. 
    
61. dnl=code_countn-1;
    
62. inl=zeros(size(dnl));
    
63. for j=1:size(inl')
    
64. inl(j)=sum(dnl(1:j));
    
65. end
    
66. 
    
67. %End-Point fit INL
    
68. %[p,S]=polyfit([1,2^numbit-2],[inl(1),inl(2^numbit-2)],1);
    
69. 
    
70. %Best-straight-line fit INL
    
71. [p,S]=polyfit([1:2^numbit-2],inl,1);
    
72. inl=inl-p(1)*[1:2^numbit-2]-p(2);
    
73. 
    
74. disp('End Points Eliminated for DNL and INL Calculations');
    
75. figure;
    
76. plot([1:2^numbit-2],dnl);
    
77. grid on;
    
78. title('DIFFERENTIAL NONLINEARITY vs. DIGITAL OUTPUT CODE');
    
79. xlabel('DIGITAL OUTPUT CODE');
    
80. ylabel('DNL (LSB)');
    
81. figure;
    
82. plot([1:2^numbit-2],inl);
    
83. grid on;
    
84. title('INTEGRAL NONLINEARITY vs. DIGITAL OUTPUT CODE');
    
85. xlabel('DIGITAL OUTPUT CODE');
    
86. ylabel('INL(LSB)');

学习一下。