how to generate saw tooth wave

I want to generate saw tooth wave,i have used m files to generate and liked in simlink ,now i want to generate sawtooth where the input to that is from pwm,kindly tell how to generate sawtooth pulse

I also tried from

http://www.electroschematics.com/571/audio-frequency-generator/

but the thing is that the pulse generator i used is not connecting with diode, kindly suggest some idea