| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a Colpitts oscillation circuit that prevents abnormal oscillation at frequencies other than a desired one and outputs a frequency signal with a satisfactory phase noise characteristic.SOLUTION: The Colpitts oscillation circuit includes: a resonance circuit including a SAW resonator 1 and an extension inductor L; and an amplification circuit including a transistor 2 for amplifying an output from the resonance circuit. The amplification circuit is so configured that a phase adjusting inductor Lis provided between a base of the transistor 2 and the extension inductor L, and that one end of capacitors C1, C2 connected in series is connected to a point between the extension inductor Land the phase adjusting inductor Lwhile the other end thereof is grounded. This adjusts the phase of a signal input into the base of the transistor 2 to suppress abnormal oscillation at a self-resonant frequency of the SAW resonator 1 and the extension inductor L, and also dispenses with a damping resistor and prevents a drop in Q value to output a desired frequency signal with a satisfactory phase noise characteristic.</p> |
