| 摘要 |
PURPOSE:To perform precise D/A conversion by making a counter count up or down by comparing tuning voltages to a control voltage by two comparators. CONSTITUTION:A voltage set by variable resistor 1 for tuning-voltage regulation is applied to transistors 2 and 4 to develop tuning voltages VR and VR-DELTAV. To obtain voltage VT controlling actual tuning operation, a numeral that corresponds to a binary numeral indicated by counter 7 is read out of memory circuit 8 and then D/A-converted. To comparators 5 and 6, voltages VR, VR-DELTAV and VT are previously input respectively; when VR-DELTAV>VT, counter 7 is instructed to count up and when VT>VR, counter 7 to count down. Tuning voltages can therefore be controlled within an error of fine voltage DELTAV all the time. |
