| 摘要 |
PURPOSE:To simplify the circuit with high accuracy by supplying a reference voltage from the same switch tree to a capacitor C of the high-order N-bit and a capacitor C/2M of the low-order M-bit so as to apply nearly the same voltage to the capacitors C and C/2M. CONSTITUTION:Nearly the same voltage obtained from the same switch tree is fed to the capacitor C forming a signal of the high-order N-bit and the capacitor C/2M being the capacitance value of 1/2M of the capacitor C to form a signal of the low-order M-bit. Thus, since the capacitance ratio of the capacitors C, C/2M is kept with a high accuracy, an A/D conversion output with high accuracy is obtained. Further, an MOS capacitance having a voltage dependancy is used. Thus, the highly accurate A/D converting circuit by a conventional MOS integrated circuit is obtained without adding a special manufacture process. Moreover, the number of switch trees and voltage dividing resistors in use is reduced remarkably.
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