| 摘要 |
The oscillating apparatus according tho this invention comprises a pulse doped FET 1, and a series feedback capacitor 2 connected to the source of the pulse doped FET 1, the pulse doped FET is a FET formed on a pulse doped epitaxial layer including a channel layer 23 with a high carrier density, and a cap layer 24 with a low carrier density formed on the channel layer 23. The series feedback capacitor 2 is a variable capacitor whose capacitance value increases when a gate bias voltage of the pulse doped FET 1 is changed toward increase a drain current of the pulse doped FET 1, Consequently it is possible to reduce phase noises by controlling only the gate bias with an oscillation frequency set at a required value. As a result, the merits of the MMIC can be sufficiently utilized without the necessity of externally adding a dielectric resonator.
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