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A phase-locked loop or phase lock loop (PLL) is a control system that generates an output signal whose phase is fixed relative to the phase of an input signal. Keeping the input and output phase in lockstep also implies keeping the input and output frequencies the same, thus a phase-locked loop can also track an input frequency.
A first linear mathematical model of second-order CP-PLL was suggested by F. Gardner in 1980. [2] A nonlinear model without the VCO overload was suggested by M. van Paemel in 1994 [3] and then refined by N. Kuznetsov et al. in 2019. [4] The closed form mathematical model of CP-PLL taking into account the VCO overload is derived in. [5]
By adding additional logic gates to the chain of flip-flops, other division ratios can be obtained. Integrated circuit logic families can provide a single-chip solution for some common division ratios. Another popular circuit to divide a digital signal by an even integer multiple is a Johnson counter.
Digital phase detectors can also be based on a sample and hold circuit, a charge pump, or a logic circuit consisting of flip-flops. When a phase detector based on logic gates is used in a PLL, it can quickly force the VCO to synchronize with an input signal, even when the frequency of the input signal differs substantially from the initial ...
Jitter is a form of phase noise that must be minimised in applications such as radio receivers, transmitters and measuring equipment. When a wider selection of clock frequencies is needed the VCXO output can be passed through digital divider circuits to obtain lower frequencies or be fed to a phase-locked loop (PLL). ICs containing both a VCXO ...
The PLECS software is available in two editions: PLECS Blockset for integration with MATLAB®/Simulink®, and PLECS Standalone, a completely independent product. When using PLECS Blockset, the control loops are usually created in Simulink, while the electrical circuits are modelled in PLECS. PLECS Standalone on the other hand can be operated ...
Process variations occur when the design is fabricated and circuit simulators often do not take these variations into account. These variations can be small, but taken together, they can change the output of a chip significantly. Temperature variation can also be modeled to simulate the circuit's performance through temperature ranges. [8]
A frequency synthesizer is an electronic circuit that generates a range of frequencies from a single reference frequency. Frequency synthesizers are used in devices such as radio receivers, televisions, mobile telephones, radiotelephones, walkie-talkies, CB radios, cable television converter boxes, satellite receivers, and GPS systems.