INTERFERENCE-FREE MULTIVIBRATOR SWITCHING CIRCUIT USING SATURATED UNDOPED TRANSISTORS WITH LARGE BASE-TO-EMITTER CAPACITY

摘要

1,169,110. Multivibrator. WILMOT-BREEDEN Ltd. 16 May, 1968 [14 June, 1967], No. 27400/67. Heading H3T. In a multivibrator, such as a bi-stable, having transistors 10, 11 which alternately saturate and cut off, the base current of each saturated transistor is at least five times the value required to just saturate it in the worst conditions, and the transistors have a large emitter to base capacity when saturated and have undoped emitter-base regions to prevent internal leakage of any stored charge. Discharge of the capacity when a transistor turns off is through the external base circuit. A saturation time constant of 1 Ás is achieved which is a comprise between immunity from interference and speed of switching. The circuit may be integrated. The value of the base current required to just saturate the transistor in the worst conditions is the maximum collector current of the saturated transistor divided by the minimum physically realizable common emitter current gain, and the operating base current is preferably between five and ten times this value.