Fast voltage-controlled pulse generator

fast voltage-controlled pulse generator 1441 Certain measuring and process con- trol applications require pulse generator sections which are to operate over a large frequency range and must, therefore, produce a signal with very low pulse width. It is for this reason that the proposed circuit uses high-speed complementary MOS (HCMOS) type gates; the proto- type typically produced an output pulse width of 20 ns over the fre- quency range of several hundred hertz to 25 MHz. The combination ICI-TI is a voltage- controlled current source which discharges C2. The fast charging of this capacitor is effected through the voltage at the output of Schmitt trig- ger NI-lb-DI. The lower frequency limit of the proposed circuit mainly depends on the offset voltage of opamp ICI. In order to enable set- ting the lower frequency limit, Ti must be arranged so as not to draw R2 any current at an input voltage of OV; to this end, offset preset PI should be correctly adjusted. Finally, the output puls...