Constant-voltage power supply circuit and amplifier circuit and DA converter using the constant-voltage power supply circuit

摘要

A constant-voltage power supply circuit having a light- emitting element and a photosensitive element optically coupled with each other and a driving power source for driving the light emitting element, the circuit using an output voltage of the photosensitive element as a reference voltage; and an amplifier circuit using a constant current converted from the reference voltage of the constant-voltage power supply circuit; and a DA converter adapted for delivering binary digital signals to the constant-voltage power supply circuit.