| 摘要 |
PROBLEM TO BE SOLVED: To provide an A/D converter utilizing a V-F conversion to conduct an AD conversion very accurately, without having to enhance the conversion frequency. SOLUTION: Two VCOs are provided and a V-F conversion value of the period or shorter of a main VCO is calculated by utilizing the periodic difference of both VCOs. The high-order bit of a digital signal is generated, by calculating the number of pulse of a pulse signal output from BASE-VCO 1 by a counter 4. Meanwhile, a lower bit is generated, by calculating a phase difference from the beginning within a sampling period to a first pulse generation within the sampling period of the output of the BASE-VCO 1 by a third register 10 and the second and third subtractors 11 and 12 each sampling period, based on the number of pulse of the output of the BASE-VCO 1, included between an activation time of a present sampling signal Ps and a phase coincidence time of the outputs of the BASE-VCO 1 and JAW-VCO 2. COPYRIGHT: (C)2007,JPO&INPIT
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