This invention aims to provide a voltage-frequency conversion circuit with high precision in a simple manner.A resistive element 16 is provided between an input terminal and a node N0. A switch element 15 is provided between a node N0 and a ground voltage GND, the switch element 15 being turned on in response to the voltage level of the node NC. A resistive element 13 is provided between the node N0 and a node NA. A resistive element 12 is provided between the node NA and one side of an input node of an NOR circuit 11A. A condenser 14 is connected between the node NA and the node NC. The input node of the NOR circuit 11A is connected with the node NA and the ground voltage GND through the resistive element 12. The input node of the NOR circuit 11B is connected with the output node of the NOR circuit 11A and the ground voltage GND. The input node of the NOR circuit 11C is connected with the node NC and the ground voltage GND.本發明以利用簡易方式提供高精度電壓-頻率變換電路作為課題。在解決手段上,電阻元件16設於輸入端子與節點N0之間。開關元件15設於節點N0與接地電壓GND之間,因應於節點NC的電壓位準而導通。電阻元件13設於節點N0與節點NA之間。電阻元件12設於節點NA與NOR電路11A的輸入節點之一側之間。電容器14連接於節點NA與節點NC之間。NOR電路11A的輸入節點藉由電阻元件12與節點NA、及接地電壓GND連接。NOR電路11B的輸入節點與NOR電路11A的輸出節點、及接地電壓GND連接。NOR電路11C的輸入節點與節點NC、及接地電壓GND連接。NA,NB,NC,N0‧‧‧節點12,13,16‧‧‧電阻元件14‧‧‧電容器15‧‧‧開關元件11A,11B,11C‧‧‧NOR電路34‧‧‧電壓-頻率變換電路
