[¦sig·mə ¦del·tə ‚an·ə‚läg tü ‚dij·əd·əl kən‚vərd·ər] (electronics) A converter that uses an analog circuit to generate a single-valued pulse stream in which the frequency of pulses is determined by the analog source, and then uses a digital circuit to repeatedly sum the number of these pulses over a fixed time interval, converting the pulses to numeric values.