Parasitic capacitance
From Wikipedia, the free encyclopedia
In electrical circuits, parasitic capacitance is capacitance that is not taken into account when considering ideal circuit elements. This extra capacitance usually has detrimental effects on the operation of "real life" circuits, reducing their bandwidth or enhancing their susceptivity to interference.
Take an example of relaxation oscillator circuit, where in the charging and discharging time of the capacitor determines the frequency. Lot of times because of the parasitic capacitance the charging and discharging time will vary.
When ever parasitic capacitance is present that capacitor will be charged. Hence expected voltage levels will not be present in the circuits.
One way of eliminating the parasitic capacitance is to add high value resistance between base and emitter of the BJT.
