Abstract
The differential non-linearity (D.N.L.) of an A-D converter (A.D.C.) is the most influential characteristic to the measurement of probability density function (P.D.F.) of random signals. We have already established in (1) the method to measure P.D.F., reducing D.N.L., under the condition in which a successive approximation type or a parallel type A.D.C. is used. This kind of A.D.C. has a short conversion time and is used in various fields, but has a relatively large D.N.L.. For this reason, this kind of A.D.C. is scarcely used in the measurement of P.D.F..
This paper presents another new method to measure P.D.F., reducing D.N.L., under the same condition. In the new method, a supplementary ramp signal is employed to average the least significant divisions of A.D.C.. The following results are obtained. [1] This new method enables one to detect the probability jump that corresponds to a discontinuity in a probability distribution function or a thin spectrum in the P.D.F.. [2] The conversion speed is increased as compared with the old method in (1). Finally, the experiments are carried out to verify the effect of this method.
