Doepfer - A-196: Phase Locked Loop (PLL)

Manufacturer Description: Module a-196 contains a so-called phase locked loop (pll). the basic pll system is shown in the sketch at the bottom of this page. a pll consists of three parts: voltage-controlled oscillator (vco), phase comparator (pc), and low-pass filter (lpf). all parts are normally connected to form a closed-loop frequency-feedback system. this is how a pll works: the output of the internal vco (linear cv control, rectangle output) is compared with an external signal (e.g. the rectangle output of a a-110 vco) in the so-called phase comparator (pc). the output of the phase comparator is a digital signal (low/high/tristate) that indicates if the frequency resp. phase difference of the two input signals is negative, zero or positive. the output of the phase comparator is processed by a low pass filter (lpf) to generate a smooth voltage that is used to control the frequency of the internal vco. the 3 units vco, pc and lpf form a feedback loop that works like this: the contro