| 摘要 |
<p>An A/D converter, which utilizes a V/F conversion, can perform an A/D conversion with high precision without raising the conversion frequency. Two VCOs are provided to utilize a difference in period therebetween, thereby determining a V/F conversion value that is shorter than the period of the main VCO. A counter (4) is used to count the pulses of a pulse signal outputted from the BASE-VCO (1), thereby generating the higher-order bits of a digital signal. On the other hand, the lower-order bits are generated by using the third register (10) and the second and third subtractors (11,12) to calculate, with respect to each sampling period, the phase difference between the beginning of the sampling period and the occurrence of the first pulse of the output of the BASE-VCO (1) within the sampling period on the basis of the number of the pulses of the output of the BASE-VCO (1) that are included in the interval between an activation of the present sampling signal (Ps) and an coincidence in phase between the output of the BASE-VCO (1) and that of the JAW-VCO (2).</p> |
