Trivial phase loop problem 5, the role of phase locked loops

You can call pll at the top level, pay attention to the use of adding a bufg to the output of pll and send it to four verilog files for use.

That prompt doesn't mean that the CLK is already in use, but that the CLK's pins aren't clock pins.

Call PLL in the top file to generate a system clock; In other files, this system clock can be entered as a clock;

I don't know if I understand it right;

Voltage controlled oscillator (used to generate signal), so the name is to adjust the frequency and phase of the output signal according to the voltage of the input signal (the voltage is the error between the input signal and the standard signal) (the change of frequency will lead to a change in phase), because it is a loop, so it is compared with the input signal until there is no error, then the input of the voltage controlled oscillator is zero, then its output is unchanged. In this way, the phase of the input signal can be stably locked, so it is called a phase-locked loop.

The purpose is to change the frequency of the received modulated signal to a frequency that is consistent with the natural frequency of the system.

As a result, the internal circuit structure can be used to accept a wide range of frequencies without changing the structure.

Yes, as long as the phase is off, an error signal will be output.

The phase-locked loop is mainly composed of a voltage-controlled oscillator, a phase detector, a low-pass filter, and a reference frequency oscillator. Voltage-controlled vibration mainly realizes the conversion of voltage and frequency, and phase discriminator mainly realizes the comparison of the frequency of voltage-controlled vibration with the frequency of the reference frequency oscillator. The low-pass filter mainly filters out the high-frequency components in the signal, and the reference frequency oscillator provides the reference frequency.

The frequency bands used by the general frequency source are different, there are more general frequency points in the industry, when some special frequency points are not very general, you can use the general frequency points to lock the phase to these special frequency points, which reduces the cost, otherwise the cost of producing the frequency points you need alone is very high, and even can not be realized, such as some frequencies are relatively high, in addition, the phase locking is not necessarily a frequency doubling, but also through the phase identification and frequency division, now the phase-locking technology is developing rapidly, A certain frequency band can be programmed to be phase-locked to any frequency in a wider range, but it can be accurate to a few decimal places, in addition, the front and rear waveforms that come out through the phase-locked loop are not exactly the same, generally if you use the chip to lock the phase have shaping, the general output is CMOS or TTL waveform.

To put it simply"loops"Theory in the phone.

Phase-locked loop (phase-locked loop): a method to make the frequency more stable in radio transmission, mainly VCO (voltage controlled oscillator) and PLL IC, voltage controlled oscillator gives a signal, part of it is used as an output, and the other part is compared with the local oscillator signal generated by PLL IC through frequency division, in order to keep the frequency unchanged, the phase difference is required not to change, if there is a change in phase difference, the voltage at the voltage output end of the PLL IC changes, Control the VCO until the phase difference is restored! Achieve the purpose of frequency locking!

Closed-loop electronic circuits that enable the frequency and phase of a controlled oscillator to maintain a definite relationship with the input signal.

The phase-locked loop consists of a phase detector, a loop filter, and a voltage-controlled oscillator. The phase detector is used to identify the phase difference between the input signal UI and the output signal UO, and outputs the error voltage UD. The noise and interference components in UD are filtered out by a low-pass loop filter, and the control voltage of the voltage controlled oscillator (VCO) is applied to the voltage controlled oscillator The result of acting on the voltage controlled oscillator is to pull its output oscillation frequency fo towards the loop input signal frequency Fi, and when the two are equal, the loop is locked, which is called locking.

The DC control voltage that maintains the lock is provided by the phase detector, so there is a phase difference between the two input signals of the phase detector. Phase-locked loops were originally used to improve line synchronization and frame synchronization of television receivers to improve immunity to interference. In the late 50s of the 20th century, with the development of space technology, phase-locked loops were used for tracking, telemetry and remote control of space targets.

In the early 60s, with the development of digital communication systems, phase-locked loops became more and more widely used, such as extracting reference carriers for coherent demodulation, establishing bit synchronization, etc. Phase-locked frequency discriminators for FM signals with threshold expansion capability were also developed in the early 60s. In terms of electronic instruments, phase-locked loops play an important role in instruments such as frequency synthesizers and phase meters.

The advantages and disadvantages are relative.

It's comparative.

What do you compare a phase-locked loop to?