| 摘要 |
PURPOSE:To miniaturize a device and to attain control by connecting a source terminal of an FET to an end of an inductance, a capacitor and a diode respectively and then connecting the other end of the inductance and the capacitor to a reference voltage source respectively. CONSTITUTION:The signal supplied through a terminal 11 is amplified by an FET12 and appears at a node 19. This signal is delivered from a signal output terminal 28. In this case, the tuning frequency is decided by an inductance 14, a capacity 15, the capacity of a diode 16 which is always used in an adverse bias state as a variable capacity and the capacity of the FET12 viewed from the node 19. Then the capacity of the diode 16 and the reverse bias voltage of the node 19 are varied by a bias control power supply 22 to control the capacity value. Thus the tuning frequency is controlled. Here both the inductance and the capacity are integrated on the same chip, and the tuning frequency is controlled electrically. Thus the device can be miniaturized with easy controll.
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