CURRENT SOURCE HAVING A HIGH TOLERANCE FOR CHANGING ENVIRONMENTAL CONDITION

摘要

A current source is provided to supply stable currents insensitively to environmental change while obtaining wide output ranges even at low power supply voltage, thereby preventing excessive power consumption. A voltage regulator determines an output voltage by using an input voltage. A plurality of transistors(40) is connected in parallel between the output terminal of the voltage regulator and a ground. A detecting unit(30) selects any one of the plurality of transistors on the basis of phase changes in the delayed clock. The selected transistor is operated.