| 摘要 |
PURPOSE:To absorb the variation of a current and to bring the variation of the initial oscillation frequency and the control sensitivity within a prescribed range by dividing a current deciding the oscillation frequency into two, passing them into transistors (TRs), applying a control signal to a base of a TR and a constant voltage to the other TR and setting the emitter current ratio of the TRs to >=1:2. CONSTITUTION:TRs Q14, Q'14 are provided and the initial oscillation frequency variation is absorbed by the emitter current I02 of the TR Q'14 so as to adjust the frequency by using an externally mounted circuit to an IC pin 2' with good yield. The oscillating frequency fvco is in variation of + or -30% depending on the variation of the capacitor C1. In order to absorb it, it is necessary for the current I0 to be changed in the range of + or -30%. In setting a design center value I01av14 of the current I01 to 1/3 of a design center value I02av15 of the current I02 in the current I0, the trimming by resistors R13, R14 have only to vary the current I02 to 40-110% of the current Iav. |
