The present disclosure relates to the technical field of semiconductors, and discloses a current source and a digital to analog convertor. The current source includes a current output circuit and an impedance gain circuit which is configured to increase output impedance of the current output circuit. The current output circuit includes a first PMOS transistor and a second PMOS transistor. The impedance gain circuit includes a first end, a second end, a third end which is connected to a supply voltage, and a fourth end which is connected to the ground. A source electrode of the first PMOS transistor is connected to the supply voltage, a drain electrode of the first PMOS transistor is connected to a source electrode of the second PMOS transistor and the first end of the impedance gain circuit, and a gate electrode of the first PMOS transistor is controlled by a first bias voltage. A gate electrode of the second PMOS transistor is connected to the second end of the impedance gain circuit, and a drain electrode of the second PMOS transistor serves as an output end of the current source.