Semiconductor driver for producing switching and offset signals.

摘要

A semiconductor intergrated circuit device for applying to an external load connectable between an output terminal (7) and a power supply terminal (1), a switching signal and an offset signal in superposed relation to each other. An offset signal supplying circuit for supplying an offset signal to the output terminal (7) is comprised of a first field effect transistor (Q19) having a drain electrode connected to the output terminal, and a second field effect transistor (Q18) having the substantially same characteristics as the first field effect transistor (Q19). The second field effect transistor (Q18) has a drain electrode connected to a source electrode of the first field effect transistor (Q19), a gate electrode connected to a control terminal (6) receptive of a control signal effective to control the offset signal, and a source electrode connected to a negative power supply terminal. A constant-voltage generating circuit (28) for generating and applying a constant voltage to a gate electrode of the first field effect transistor (Q19) is comprised of a resistor (R11) connected between a positive power supply terminal (1) and the gate electrode of first field effect transistor (Q19), and a plurality of diodes (D13-16) having the substantially same characteristics and being forwardly series-connected to each other such that an anode of the first stage diode is connected to the gate electrode of the first field effect transistor (Q19) and a cathode of the last stage diode is connected to the negative power supply terminal (2) so that a voltage between the series-connected diodes is set to half of a power supply voltage applied between the positive and negative power supply terminals, each of the diodes having an internal resistance smaller than a specific resistance of the resistor.