| 摘要 |
PURPOSE:To attain high speed and high accurate control of an oscillating frequency without changing the current consumption by providing a cathode coupling diode pair between sources of FETs forming a source coupling switch and varying the applied voltage of the cathode. CONSTITUTION:The oscillating frequency f0 of the circuit is expressed as f0=I/(4C+phiB), where I is a drain current flowing to FETs Q3, Q4, c is a combined capacitance between a capacitor C1 and junction capacitance of diodes D5, D6 and phiB is a barrier capacitance of the diodes D1, D2. The capacitance C is expressed as C=C1+1/2CP, where C1 is the capacitance of the capacitor C1, and CP is the junction capacitance of the diodes D5, D6. Moreover, the capacitance CP is expressed as CP=C0/(phiB-Vf)<1/2>, where C0 is a constant decided by the structure of the diodes and Vf is a forward bias voltage applied to the diodes. Thus, the oscillating frequency f0 is controlled by varying the bias voltage applied from the voltage source VCO of the oscillation frequency control to the cathode of the diodes D5, D6. Since the current 1 is always constant, no temperature change is caused and the frequency f0 is made stable.
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