To provide an oscillation circuit that can improve accuracy of an oscillation frequency.
The oscillation circuit comprises: a reference voltage generation circuit that adds and outputs a PTAT output and a CTAT output; a first switch means that switches an addition ratio to minimize output voltage fluctuations of the temperature-dependent reference voltage generation circuit; a current source that generates a constant current based on the output voltage of the reference voltage generation circuit; a regulator circuit that generates a constant voltage based on the output voltage of the reference voltage generation circuit; a first capacitance and a second capacitance whose one end is connected to the current source to be charged and discharged by the constant current of the current source; an inverter that drives the other end of the second capacitance by the use of the constant voltage supplied from the regulator circuit as a power source; a second switch means that switches the constant current value of the current source to trim an oscillation frequency; and a third switch means that switches the capacitance value of the first capacitance to trim an oscillation amplitude at the one end of the first capacitance and the second capacitance. The oscillation circuit generates a desired amount of constant frequency by trimming with the first switch means, the second switch means, and the third switch means.
OKADA KOJI
TACHIBANA MASARU
