Patent ID: 6703958
Filing Date: 2004-03-09
Classification: H03M

Abstract:
An analog-to-digital (A/D) converter circuit that converts an external analog signal sequentially generated from an external analog signal source into an n-bit digital data signal (n being an integer equal to or more than two), comprising:a digital-to-analog (D/A) converter circuit that converts a prior n-bit digital data signal into an analog signal and outputs the analog signal from a first output terminal; a comparator that compares a signal level of an external analog signal supplied from an external device with a signal level of the analog signal outputted from the first output terminal; and a digital integrator circuit that digitally integrates a 1-bit digital data signal outputted from said comparator and thereby produces the prior n-bit digital data signal and outputs an n-bit digital data signal to an external device, wherein the comparator also outputs the 1-bit digital data signal via a second terminal, and said digital integrator circuit includes: an up-down counter that conducts an addition or a subtraction for a value thereof according to the 1-bit digital data signal outputted from said comparator and produces an n-bit count value, and an adder including a first input terminal, a second input terminal, and a third output terminal, the first input terminal receiving the n-bit count value from said up-down counter, the second input terminal receiving a prior n-bit value, the third output terminal outputting the n-bit digital data signal as a result of the addition of the first input terminal and the second input terminal.