| 摘要 |
PURPOSE: An analog signal analyzing circuit is provided which gradually varies a terminal voltage applied across a resistor for generating a reference voltage using a bus interface of a PC and a D/A converter to analyze analog input signals based on data values that are output whenever the terminal voltage is varied. CONSTITUTION: An analog signal analyzing circuit includes a reference voltage generator(1), a comparison unit(2), D/A converters(3A,3B) and a control logic(4). The reference voltage generator divides a voltage applied across a power supply port using a predetermined number of serial resistors to generate reference voltages(Vref0-Vref3). The comparison unit compares an input analog signal(AS) with the reference voltages respectively using a plurality of comparators and generates comparison data(D0-D3) based on the compared result. The D/A converters convert an input digital voltage into an analog voltage to provide the analog voltage to the power supply port of the reference voltage generator. The control logic sequentially varies a digital voltage value using code values supplied through a bus of a PC to provide the digital voltage value to the D/A converters, and reads the data output from the comparison unit to measure the voltage value of the analog signal.
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