| 摘要 |
PURPOSE:To execute an A/D conversion whose temperature drift is small, by representing an output which has compared an input analog signal, and a pseudo random signal having amplitude whose probability density distribution is constant, by a pulse whose period is constant, and integrating it at every time of integer times of an external noise period. CONSTITUTION:An input analog signal f (t) is amplified at 1, and after that, is compared with a pseudo random signal P (t, x) 3. If an amplitude probability density function of the signal P is constant, the probability of f>P is in propeortion to (f). A pulse SP of a period Ts is generated 4, a comparison output 2 is represented, and is counted at 6. On the other hand, the pulse SP is frequency-divided at 7 into 1/N, is reset by a pulse Tc=NTs, a pulse having a period Tc is provided to a strobe terminal S of a latching circuit 8, too, a counting value is latched, and a digital output is obtained. In this regard, when this converter is used in a place where a periodical noise occurs, a noise can be removed by selecting Tc to integer times a period of a noise component. Since this converter has no RC circuit, it is free from a temperature drift, and a very small signal can be converted enough. |
