Well Linearity Sawtooth Wave Generator Based on 555 Timer

The basic principle of the sawtooth-wave generator which designed by the 555 timer was analyzed briefly.The key condition that the timed capacitor must charged by constant current and discharge quickly to the well linearity sawtooth-wave generator was pointed out.In consideration of different circuit can provide constant current,three kinds of concrete methods which can generate well linearity sawtooth-wave have been put forward:bootstrap type,constant current source type,and voltage-current converter type.And their respective characteristic was analyzed,the formula to calculate the frequency of the sawtooth wave which generated by these methods was pointed out.The sawtooth wave which generated by these methods has well linearity,this was demonstrated by the experiments.