Binary weighted current source and digital-to-analog converter

A digital-to-analog converter, including:

• a binary weighted current source, including:
• a driving voltage generating circuit, generating a driving voltage based on a preset current;
• a current dividing circuit, connected to an output terminal of the driving voltage generating circuit,
• wherein the current dividing circuit divides the driving voltage through resistors in series, and drives each of a plurality of current output transistors to output a current in response to a voltage across the current output transistor,
• wherein currents output by the plurality of current output transistor are binary weighted currents, each two of the binary weighted currents have a binary relationship, and the binary weighted currents are produced by successive binary divisions of the preset current,
• wherein each of the binary weighted currents and a voltage cross the corresponding current output transistor have an exponential relationship between them;
• a current steering circuit, connected to the current dividing circuit and used to control currents passed by the resistors in series;
• a plurality of current dividing circuits, wherein the plurality of current dividing circuits are cascaded in sequence;
• and
• a plurality of current steering circuits, wherein each of the plurality of current steering circuits corresponds to one of the plurality of current dividing circuits;
• and
• a digital-to-analog converting circuit, wherein the digital-to-analog converting circuit is connected to the binary weighted current source and produces analog signals based on digital signals and the binary weighted currents.