PURPOSE: To set the variable range of the output current optional by connecting a reference current source to a 1st current mirror circuit, using an output of a 1st amplifier for a reference potential application point and giving 1st to n-th outputs of a 2nd current mirror circuit to n-sets of weighting terminals of an R-2R resistor ladder circuit.

CONSTITUTION: A current of a reference current source 1 is given to a 1st current mirror circuit comprising transistors(TRs) 2-3 and resistors 5-7, its 1st output is inputted to a current-voltage circuit comprising a resistor 9 and an amplifier 8, in which the output is converted into a voltage and it is used for a reference voltage for an R-2R ladder circuit comprising resistors 24-29. A 2nd output of the 1st current mirror circuit is given to a 2nd current mirror circuit having n-sets of outputs comprising TRs 10-14 and resistors 15-19 and n-sets of outputs are given to n-sets of control current terminals to the R-2R resistor ladder circuit via switches 20-23 to decide an output voltage of the R-2R resistor ladder circuit.