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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]
The phase detector needs to compute the phase difference of its two input signals. Let α be the phase of the first input and β be the phase of the second. The actual input signals to the phase detector, however, are not α and β, but rather sinusoids such as sin(α) and cos(β). In general, computing the phase difference would involve ...
Tuning gain and noise present in the control signal affect the phase noise; high noise or high tuning gain imply more phase noise. Other important elements that determine the phase noise are sources of flicker noise (1/f noise) in the circuit, [8] the output power level, and the loaded Q factor of the resonator. [9] (see Leeson's equation).
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 ...
The easiest configuration is a series where each flip-flop is a divide-by-2. For a series of three of these, such a system would be a divide-by-8. 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.
In the Control Systems jargon, the DLL is a loop one step lower in order and in type with respect to the PLL, because it lacks the 1/s factor in the controlled block: the delay line has a transfer function phase-out/phase-in that is just a constant, the VCO transfer function is instead G VCO /s. In the comparison made in the previous sentences ...
A PLL multibit or multibit PLL is a phase-locked loop (PLL) which achieves improved performance compared to a unibit PLL by using more bits. Unibit PLLs use only the most significant bit (MSB) of each counter's output bus to measure the phase, while multibit PLLs use more bits. [1] PLLs are an essential component in telecommunications.