A Phase-Locked Loop is an electric circuit that is used to modulate and demodulate an input signal from the source. The voltage-controlled oscillator adjusts the frequency of the input signals which is further used for different purposes. Phase Locked Loop is mostly used in communication systems, satellites, FMs, and Radio signals.
In this guide, you are going to learn more about the Phase Locked Loop, its block diagram, working principle, and applications. We are going to learn how to make these diagrams and what they can offer us in the long term.
In this article
What is a Phase-Locked Loop?
A PLL is a simple electronic circuit and has two working modes: Linear and Nonlinear. The non-linear mode is hard to achieve in the real world. However, linear control mode is achievable and covers a lot of areas.
Phase Locked Loop is a closed-loop feedback control system where the voltage and frequency of the system matter a lot. The initial voltage Vi and initial Frequency Fi are quite important. These circuits are not signal component circuits as they used both analog and digital components to make the whole setup.
The main goal of these circuits is to create a phase difference keeping the frequency of two signals the same. That is why these circuits are called phase-locked loop circuits. These circuits are being used in most of the technologies we have at home like WiFi signals and communication signals used in our mobile phones.
Block Diagram of PLL
Block diagrams for the Phase-locked Loop circuit describe the functions of the system and make it easier for you to understand the features and components of the circuit. It consists of the basic input signal often called the reference signal. Here is a block diagram for the phase-locked loop circuit.
There is a phase detector that is used to detect and receive the input signal from the source input. We have a loop filter that alters the frequency of the signals and makes it feasible for the system to give proper output. The voltage-controlled oscillator is used to modify the input signal if it has deficiencies.
The output signal is then used for different applications.
Working Principles of PLL
PLL or Phase Locked Loop works in three different modes. These modes include
- Free running mode
- Capture mode
- Lock mode
When there is no input applied to the system, PLL works in free-running mode. When we apply an input signal to the PLL, the frequency of the voltage-controlled oscillator starts to change, this mode is said to be the capture mode.
Once the frequency of the Output signal is equal to the input signal, this stage is said to be the lock mode. These modes are quite crucial and describe the working principle of the Phase locked Loop Circuit.
So, the input signal frequency fi is detected by the phase detector and the output for the phase detector is fi+fo which is a DC Voltage. Now, this phase detector output is a new input for the filter which is used to reduce high-frequency noise and create a stable frequency for the VCO which is fi-fo.
The VCO gives us the most stable value for the frequency and helps the circuit to attain stability. The input signal and the output of the VCO are directly proportional to each other.
Phase-Locked Loop (PLL) Fundamentals
Every part of the PLL has its value and has a purpose in the circuit whether it is a phase detector, filter, or VCO. The phase detectors are of two types i.e., XOR phase detector and phase frequency detector. Both of them serve different purposes in the circuit. However, the main function of both of the detectors is to detect the frequency of the input source and give feedback for the filter.
The filter of the circuit usually serves as a medium to collect the input signal as DC voltage. The input signal catches with the voltage and makes it possible for the VCO to match the input signal.
The Voltage Collector Oscillator provides the stable output which is proportional to the input signal.
How to Make a PLL Block Diagram
The block diagram is a good way to understand a model which has complex components. These diagrams are useful to understand and help developers manage their workload. However, for a simple system, the block diagrams are used to simplify the model by breaking them into blocks and giving these blocks a direction to know the flow of the work.
The block diagram for PLL is easier to make as there are not too many complex blocks to make. Here are a few of the steps you need to follow while making your block diagram for PLL.
Step 1:
Open an empty canvas where you are willing to make your PLL block diagram. Find Blocks from the elements and tools and place them on the canvas.
Step 2:
Give names to each and every block to make it easier to understand the model. Keep the font size the same to make it look better.
Step 3:
Add a relationship between the blocks according to the requirements of the diagram. Keep the line weight prominent so that they are prominent.
Step 4:
Add the colors in the blocks and pick a color for the background to make it look attractive.
So, that is all you need to do to make a block diagram for the PLL circuit. It is easy and quite advantageous to have these diagrams for further investigations about the model or circuit.
Bottom Line
Phase Locked Loop circuits are used to maintain the frequency of the input source and make it available for further use. The block diagrams for these circuits always play a crucial role as they help users to have a record of the model or use it for learning purposes.
When it comes to making these diagrams, they are as simple as they can get. You can draw them easily or find suitable templates from Edrawmax to adjust your block diagrams as per your needs. There are hundreds of templates available for you to pick from. You can use them to make your designs and make any change that is needed.
If you are willing to make it from scratch, EdrawMax offers the right tools to get things done quickly. You can save your designs to make any further changes to them at any time.
EdrawMax Desktop
Edraw.AI
