synchronous, constant amplitude, sawtooth generator

synchronous, constant- amplitude sawtooth generator This circuit was designed because we needed a sawtooth waveform with a well defined constant amplitude for applications in pulse-width modu- lation control systems. The circuit here is a generator that produces a sawtooth signal which can be synchronized with an input pulse. The circuit can therefore be consid- ered as a control system which is comparable with an analogue sub- routine. The average output signal level of op-amp Al is compared with a reference voltage by com- parator A2. If necessary, the two levels are equalized by means of T1 and T2. The time-constant of the control system is formed by resistor R4 and capacitor C3. If the time-constant is made too smalt, the rising edge of the sawtooth will tend to become sinusoidal and the linearity of the signal will suffer. With the values shown, the frequency range lies between 100 Hz and 5 KHz, which can be extended upwards by the use of an op-amp with a higher performance. ...