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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.
Following Gardner's results, by analogy with the Egan conjecture on the pull-in range of type 2 APLL, Amr M. Fahim conjectured in his book [8]: 6 that in order to have an infinite pull-in(capture) range, an active filter must be used for the loop filter in CP-PLL (Fahim-Egan's conjecture on the pull-in range of type II CP-PLL).
A Costas loop is a phase-locked loop (PLL) based circuit which is used for carrier frequency recovery from suppressed-carrier modulation signals (e.g. double-sideband suppressed carrier signals) and phase modulation signals (e.g. BPSK, QPSK). It was invented by John P. Costas at General Electric in the 1950s.
Since the maximum output frequency is limited to /, the output phase noise at close-in offsets is always at least 6 dB below the reference clock phase noise. [ 6 ] At offsets far removed from the carrier, the phase-noise floor of a DDS is determined by the power sum of the DAC quantization noise floor and the reference clock phase noise floor.
Silicon die of the first 555 chip (1971) Die of a CMOS NXP ICM7555 chip The timer IC was designed in 1971 by Hans Camenzind under contract to Signetics. [3] In 1968, he was hired by Signetics to develop a phase-locked loop (PLL) IC.
The terms hold-in range, pull-in range (acquisition range), and lock-in range are widely used by engineers for the concepts of frequency deviation ranges within which phase-locked loop-based circuits can achieve lock under various additional conditions.
In an injection-locked frequency divider, the frequency of the input signal is a multiple (or fraction) of the free-running frequency of the oscillator. While these frequency dividers tend to be lower power than broadband static (or flip-flop-based) frequency dividers, the drawback is their low locking range.
A binary phase accumulator consists of an N-bit binary adder and a register configured as shown in Figure 1. [5] Each clock cycle produces a new N-bit output consisting of the previous output obtained from the register summed with the frequency control word (FCW) which is constant for a given output frequency.