1. Number of Comparators Marina Artuso Jianchun Wang 08/06/01

2. Jianchun (JC) Wang2 Simple Model  Fixed intrinsic noise: Q noise = 100 e  Different threshold dispersion: Q dispersion  Threshold 0 varies: Q thresh0 = 5 (Q noise + Q dispersion )  Highest threshold: Q max = 24,000 e (1 MIP)  Logarithmic ADC: ( N = 7, 8 ) Q threshn = Q thresh0  exp(ln(Q max /Q thresh0 )  n / (N-1)) 7-comparator8-comparator Q dispersion Q thresh0 Q dispersion Q thresh0 30020004002500 40025005003000 50030006003500

3. 08/06/01Jianchun (JC) Wang3 Resolution vs Digitization Range  Same parameters except for Q max  7-threshold logarithmic ADC  Noise = 100 e  Threshold dispersion = 300 e  Threshold 0 = 2000 e  Threshold 6 = 24,000 e  f

4. 08/06/01Jianchun (JC) Wang4 Different Number of Comparators With improved threshold dispersion, 7-comparator performs better than 8-comparator

5. 08/06/01Jianchun (JC) Wang5 Different Number of Comparators With same threshold dispersion, 7-comparator performs nearly as good as 8-comparator

6. 08/06/01Jianchun (JC) Wang6 Summary  Reducing comparator number from 8 to 7 will not deteriorate the resolution.  Reducing threshold dispersion with sacrifice of 1 comparator surely is a good choice.