Oscillator for generating output signal with adjustable frequency

An oscillator, comprising:

• a resistance unit, serially connected between a first reference point and a second reference point;
• a capacitance unit, coupled between the first reference point and an output point and the capacitance unit comprising a plurality of capacitors, one terminal of each of the capacitors coupled to the output point, and the other terminal of each of the capacitors coupled to the first reference point or a reference ground according to a control signal, wherein the capacitance unit further comprises a plurality of switches, each of the switches having a first terminal, a second terminal, a third terminal, and a control terminal, wherein the control terminal of each of the switches receives the control signal, and the first terminal of each of the switches is coupled to each of the corresponding capacitors, and the second terminal of each of the switches is coupled to the first reference point, and the third terminal of each of the switches is coupled to the reference ground;
• a first inverter, having an input terminal coupled to the first reference point, and having an output terminal coupled to the second reference point;
• and
• a second inverter, having an input terminal coupled to the output terminal of the first inverter, and the second inverter having an output terminal coupled to the output point.