Device for clamping multiple signals

摘要

A large number of analog signals (Aa, Ba . . . Na) are time-division-multiplexed by an analog switch (12) into a single analog signal (c). The multiplexed analog signal (c) is converted by an A/D conversion circuit (8) into a digital signal (d). The digital signal (d) is separated by a signal separation circuit (14) into a large number of digital signals (e) respectively corresponding to the analog signals (Aa, Ba . . . Na). Each digital signal (e) is compared by a comparison circuit (9) with a digital reference value (f) having a predetermined value. A current source control circuit (10) generates a digital control signal (g) according to the amount of shift in the digital signal (e) with respect to the digital reference value (f), and the current source (11) is controlled by the control signal (g). Therefore, the clamp level of an analog signal is adjusted to a predetermined level with a high precision, thereby effectively suppressing the level shift thereof.