Phase-locked Loops (PLLs)

IC phase locked loops (PLL) are closed-loop frequency controls that are based on the phase difference between the input signal and the output signal of a controlled oscillator. An IC phase-locked loop generally consists of a phase detector, a loop filter, voltage controlled oscillator (VCO) and an amplifier. There are many types of IC phase locked loops. Examples include a digital phase locked loop, current loop driver kit, ADC phase locked loop and a synthesizer digital PLL. A digital phase locked loop circuit is used if the data and clock are to be sent together over the same cable because in this circuit the receiver separates the clock from the data received. A digital PLL chip simplifies the clock design and increases reliability of the circuit in which it is present. A current loop driver kit is a type of phase locked loop circuit in which the phase detector is not present. A current loop chip is a programmable chip and it can directly interface to the computer. In a ADC phase locked loop, the analog signal is converted into the digital signal. A synthesizer digital is a type of PLL frequency synthesizer which is an electronic device that is capable of producing frequency coherent to a reference frequency. Other IC phase locked loops (PLL) are commonly available.