| 摘要 |
PURPOSE:To improve the frequency-setting accuracy, reliability and mass-productivity, by controlling the electric charge quantity of a load element in an oscillation circuit with respect to a loating electrode. CONSTITUTION:An oscillation circuit comprising a piezoelectric oscillator 3, an oscillation amplifier 1 and a feedback resistor 2 is provided with MOS semiconductor variable-capacity elements 4 and 5 as load capacities. In this case, the fluctuation of the oscillation frequency is regulated by changing the capacities of the elements 4 and 5. Each of the elements 4 and 5 has a floating electrode 10 provided on an n type semiconductor substrate 8, said electrode 10 being covered with an oxide insulating film 9 for insulation, and a capacity electrode 11 is provided above the electrode 10 through the film 9. When a variable voltage is applied in a pulsed manner between an n type diffused layer 13 on the surface of the substrate 8 and the substrate 8 so that said layer 13 is positive-biased with respect to the substrate 8, from the electrode 10, electrons are led out into the layer 13, so that the capacity value of the electrode 10 increases. On the other hand, when the layer 13 is negative-biased, the capacity value of the electrode 10 decreases. |
