| 摘要 |
<p>An A-D converter utilizing V-F conversion is realized that is capable of performing A-D conversion with high precision without increasing conversion frequency. Two VCOs are provided to find a V-F conversion value that is less than a period of the main VCO by making use of a period difference between the two VCOs. By counting the number of pulses in a pulse signal that is output from a BASE-VCO 1 with a counter 4, a high order bit of a digital signal is generated. A low order bit, on the other hand, is generated by calculating, for each sampling period, a phase difference from the beginning of a sampling period until a first pulse generation in the sampling period for the output of the BASE-VCO 1 by a third register 10 and second and third subtracters 11 and 12, based on the number of pulses in the output of the BASE-VCO 1 contained in a period from a current activation time point of sampling signal Ps to a time point at which phases of outputs of the BASE-VCO 1 and JAW-VCO 2 match.</p> |
