FEEDBACK DIFFERENTIAL TRACKING A/D CONVERSION

摘要

The result of a measurement has uncertain value-band depending on dynamic behaviour of the measured object and measurement instrumentation. Numerical value is attained with successive approximation of the difference between the reference and measured quantity. Estimation of the difference between two levels is possible with at least two sampling pulses. The dynamic error is proportional to that difference with addition of some constant. For effectiveness of differential tracking, the non-uniform quantization must fulfill three conditions: partitions into halves, increasing quantization uncertainty with difference, and low overlapping of the quantization intervals. The best trade between the number of decision levels and the settling time is with pure exponential quantization rule. The fastest response is achievable with base 2. The conversion time can be shortened to one third in comparison with the best parallel-serial A/D conversions.