PURPOSE: To suppress as much as possible the fluctuation of frequency against power supply voltage fluctuation by using a bipolar transistor in common base connection in terms of high frequencies and loading an externally mounted capacitance circuit between the collector and emitter of the transistor.
CONSTITUTION: Fig. shows a Colpitts oscillation circuit using a common base transistor connection. A fixed capacitor 17 is used as a load to the circuit shown in Fig. Through the constitution above, suppose that a collector capacitance having a varactor element function in a conventional circuit is increased by ΔC1 from the initial capacitance C1 due to power supply fluctuation, the rate of change is expressed as ΔC1/C1, and the equivalent capacitance ratio is ΔC1/ (C1+C2) by loading the fixed capacitor 17 of a capacitance C2 between the collector 13 and base 14, that is, in parallel with the collector capacitance, the effective sensitivity is decreased and the rate of change in the capacitance against the power supply voltage is reduced.
MAKIMOTO MITSUO
YAMASHITA SADAHIKO
| JPS54101251A | 1979-08-09 | |||
| JP43008530A |