| 摘要 |
PURPOSE:To improve temperature characteristics over the entire range of oscillation frequency by setting the temperature coefficient of a variable constant current source which varies the oscillation frequency to a specific value different from the temperature coefficient of a constant current source. CONSTITUTION:The bases of transistors (TR)1 and 2 are connected to the collectors of TRs 2 and 1, so a parallel resonance circuit 11 oscillates at a roughly determined frequency. The resonance frequency of this formed VCO is varied by controlling the current flowing through the variable constant current source 8. Then, the temperature coefficient of the variable constant current source 8 is set to the specific value which is different from the temperature coefficient of the constant current source 7 and determined by the temperature coefficient of the total current of both constant current sources 7 and 8 and the variable frequency range of the VCO. Consequently, temperature characteristics at both terminals of the variable range of the oscillation frequency cancel each other and the temperature characteristics are improved over the entire range of the oscillation frequency. |
