DAC and oscillation circuit

An oscillation circuit, comprising:

• a digital to analog converter (DAC) configured to output a first voltage and a second voltage;
• and
• an oscillator configured to oscillate an oscillation signal with a frequency corresponding to a difference voltage, wherein
• the difference voltage is a difference between the first voltage and the second voltage, and
• the DAC includes:
• a voltage-dividing resistor;
• a plurality of first switches connected to the voltage-dividing resistor, wherein
• each first switch of the plurality of first switches is configured to output, as the first voltage, a voltage at a corresponding connection point of a plurality of first connection points, and
• the plurality of first connection points is between the voltage-dividing resistor and the plurality of first switches;
• and
• a plurality of second switches connected to the voltage-dividing resistor, wherein
• each second switch of the plurality of second switches is configured to output, as the second voltage, a voltage at a corresponding connection point of a plurality of second connection points, and
• the plurality of second connection points is between the voltage-dividing resistor and the plurality of second switches;
• and
• a decoder configured to transmit a control signal to the DAC, wherein
• the control signal is based on a frequency adjustment signal for adjustment of the oscillation signal of the oscillator,
• one of the plurality of first switches or the plurality of second switches are sequentially turned on from a power supply side of the one of the plurality of first switches or the plurality of second switches, respectively, based on the control signal, and
• the plurality of first switches and the plurality of second switches are controlled such that the first voltage is fixed and the second voltage is changed.