| 摘要 |
PURPOSE: An analog-to-digital converter is provided to minimize an error of a process variable by reducing a number of a capacitor. CONSTITUTION: An analog-to-digital converter includes a first reference voltage generator(22), a second reference voltage generator(24), switches(SW21-SW24,SW40), capacitors(C21,C22), and a comparator(26). The first reference voltage generator(22) responses to a high-ranking 512-bit(D(1024:513)) of digital data provided from an external, performs a partial pressing on a reference voltage(Vref) and a ground voltage(VSS), and outputs the partial pressed first reference voltage(Vmsb). The second reference voltage generator(24) responses to a low-ranking 512-bit(D(512:1)) of digital data provided from the external, performs the partial pressing on a voltage corresponding to 1/4 of the reference voltage(Vref) and a ground voltage(VSS), and outputs the partial pressed second reference voltage(Vlsb). The switch(SW21) is connected between one end of an analog signal(va) inputted from the external and the first capacitor(C21). The switch(SW22) is connected between one end of the first reference voltage(Vmsb) and the first capacitor(C21) outputted from the first reference voltage generator(22). The switch(SW23) is connected between one end of the second reference voltage(Vlsb) and the first capacitor(C22) outputted from the second reference voltage generator(24). The switch(SW24) is connected between one end of the ground voltage(VSS) and the second capacitor(C22).
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