| 摘要 |
An analog-to-digital converter includes a capacitor array circuit for determining m upper bits of a digital output, which includes a plurality of capacitors having binary-weighted capacitance ratios and a plurality of switches and which is connected to an input terminal of a sampled analog voltage and a reference voltage source. A resistor string circuit is provided for determining n lower bits of the digital output, including a plurality of switches and which is connected to the capacitor array circuit. A voltage comparator compares an output voltage of the capacitor array circuit with the ground potential and successive approximation registers successively provide pulses for controlling the switches of the capacitor array circuit and the resistor string circuit in accordance with the output of the voltage comparator. A circuit generates timing pulses for controlling the operation of the successive approximation registers. The resistor string circuit applies voltages equal to i/2n (where i denotes a value expressed by the n lower bits of the digital output) and (2n-i)/2n of a reference voltage to the capacitor array circuit, and the capacitor array circuit operates so as to put the input analog signal into a digital signal in accordance with a linear input/output conversion characteristic.
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