FET MULTIVIBRATOR CIRCUIT

PURPOSE:To decrease the temperature dependancy of an oscillated frequency by using a temperature compensation diode so as to connect a gate and a drain of a couple of FETs forming a current source. CONSTITUTION:The oscillating frequency f0 of the circuit is expressed as fo=I/4 CphiB, where I is a drain current flowing through FETs Q3, Q4, C is the capaci tance of a capacitor C1 and phiB is a barrier potential of diodes D1, D2. When temperature raises, the potential phiB of the diodes D1, D2 is lowered and since the barrier potential phiB of the diode D5 is lowered similarly in this case, the gate potential of the FETs Q3, Q4 is lowered and the drain current I flowing to the FETs Q3, Q4 is lowered. That is, the increase in the oscillating frequency fo due to the reduction in the barrier potential phiB is cancelled by the decrease in the drain current I, then the temperature dependancy of the oscillating fre quency f0 is decreased.