| 摘要 |
PURPOSE:To set an optimum operating point to dispersion of threshold value and to obtain a reference voltage source excellent in the stability, by changing a current of a constant current source through the stepwise change of a bias voltage and also of temperature. CONSTITUTION:A gate of an enhancement NMOS element 11 is connected to an output terminal 1 of a reference voltage source, the output of the element 11 and the output of a depletion NMOS element 12 are negative-fed-back to the gate of the element 11 via an operational amplifier 20, drain currents of the elements 11, 12 are made equal, and made constan at an NMOS element 15 of the constant current source. A bias circuit 100 consisting of a resistor 102 and a variable resistor 101 is connected between the gate of the elements 11 and 15. The bias voltage is stepwise changed at the circuit 100, the current of the element 15 is changed and the temperature is also changed to set an optimum operating point to dispersion of threshold value, allowing to output a stable reference voltage from the output terminal 1. |
