PURPOSE: To peform accurate converting operation, by providing a temperature compensation transistor (TR) and making the channel width of each TR different.

CONSTITUTION: Temperature compensation TRs Qf∼Qk are connected in series with resistors Za∼Zf out of resistors Za∼Zk forming a ladder circuit network, and gates of the TRs Qf∼Qk are applied with a voltage Vb higher than a power supply voltage Va for conversion and a voltage of a digital signal inputted to input terminals IaA∼Ieb. The channel width of switching TRs Qaa∼ Qeb is made different, the fluctuation of resistance value of the TRs Qaa∼Qeb is suppressed due to the change in the digital signals, and the channel width of the TRs Qf∼Qk is formed in a prescribed ratio based on the channel width of the TRs Qaa∼Qeb.