PLL-controlled ramp generator

The CD4046 is an integrated phase-Iocked loop (PLL) with integral voltage-controlled oscillator (VCO) that is used in many digital circuits. In the present circuit, the VCO is used to generate a sawtooth stgnal. Normally, the VCO produces a triangular signal that is compared with an external digital signal. The VCO in the standard 4046 can be used for digital signals up to 1 MHz; in the HC or HCT version it is usable up to 38MHz.