| 摘要 |
PURPOSE:To increase the variable frequency range together with improvement of stability for a variable frequency oscillating circuit and at the same time to convert this circuit suitably into an IC, by making use of the exponential function characteristics of a transistor (TR) to correct the control current to obtain the linear control signal/oscillation frequency characterisitcs. CONSTITUTION:A current I13 flows to a resistance R11 from an amplifier 13, and as a result the collector current I16 of a TRQ16 is equal to that obtained by multiplying the saturation current Is of the TRQ16 by the exponential function of the difference between the base-emitter voltage a TRQ17 and (I13XR11). As a TRQ19 and a TRQ15 constitute a current mirror circuit 14, the collector current I5 of a TRQ5 is equal to I16. Therefore I5(0) is equal to the value obtained by multiplying the current Is by the exponential function of the base voltage of the TRQ17 when the current I5 is equal to I5(0) when I13=0 is satisfied. As a result, I5(0)/I5 is obtained as the exponential function of I13. Then the current I5 changed in terms of an exponential function from the standard I5(0) to I13. Therefore the oscillation frequency has a linear change to the current I13. |
