| 摘要 |
PROBLEM TO BE SOLVED: To switch the ON/OFF operation of first differential couples M1 and M2 for oscillation and second differential couples M3 and M4 for amplification and output and to eliminate a loss caused by such switching in simple configuration, concerning an oscillation circuit 11, with which the oscillated signal of any frequency is selectively outputted, provided with the first differential couples M1 and M2 for respectively performing oscillation with plural frequencies determined by resonance circuits N1 and N2. SOLUTION: The emitters of transistors Q1-Q4 comprising the differential couples M1 and M2 are commonly connected to a first constant current circuit F1 and the emitters of transistors Q5-Q8 comprising the differential couples M3 and M4 are commonly connected to a second constant current circuit F2. Therefore, when the oscillation current of the differential couples M1 and M3 on one side is increased by the difference of DC bias voltages V1 and V2, the oscillation current of the differential couples M2 and M4 on the other side is decreased and oscillation is stopped. Thus, the configuration of ON/OFF operation in the constant current circuits F1 and F2 can be eliminated.
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