DIGITAL CONTROLLED OSCILLATION CIRCUIT

PROBLEM TO BE SOLVED: To reduce the frequency error by providing an AFC circuit and storing a correction value to a memory as a value corresponding to an output value from a temperature sensor at that time as soon as the correction value is outputted to a correction circuit. SOLUTION: Let an error between a frequency (f) outputted from an oscillation circuit and a frequency of a radio wave received from a base station or the like at that time be f0 , an IF section 7 and an RF section 8 provide a frequency output of f0 , an AFC circuit 9 calculate a frequency shift Δf based on the frequency f0 and it is outputted to a CPU 3. The CPU 3 applies a value corresponding to the Δf to a D/A converter 4 as a correction value. Simultaneously the D/A conversion value DA2 and the A/D conversion value AD2 at that time are stored newly in a memory 6 as the correction values. Since the CPU 3 applies the value corresponding to the Δf to the D/A converter 4 as a correction value, the frequency error is reduced. Furthermore, since the D/A conversion value DA2 and the A/D conversion value AD2 are newly stored in the memory 6 as the correction values, the values with higher frequency accuracy are used.