Technical
How to Judge the Acceptance of PCB Quality
Which Color Circuit Board Sells the Most Expensive
Method to Solve the Noise Interference of Power Supply on High-frequency PCB Board
Disassembly Skills of Chip Components on PCB
What Factors Should Be Considered in the Selection of High-frequency PCB CCL
How to Place Special Components during PCB Layout
What Are the Functions of Capacitors in Circuits?
Testing Techniques for Common Electronics Components
What to do if There is a Short Circuit on the PCB
Desoldering Principles and knowhow during PCBA Processing
Black Oxidation of the Inner Layer of the Multilayer PCB
How to Ensure the High-performance Design of PCB
What Is the Printing Process of SMT Solder Paste?
PCB without fiducial mark, Is There Any Way to do SMT for It
What Are the Benefits of Reserving Break-up Tab for PCB Production
How Does SMT Affect PCB Production Time and Speed It Up
Classification of PCBs from three aspects
Common Problems and Solutions for Dry Film pasting during PCB Manufacturing process
Several Elements to Inspect after PCB Design
What is a halogen-free circuit board?
What Do Capacitive Coupling and Decoupling Mean?
What Are the Differences Between PCB Paste Mask and Solder Mask?
How PCBA Is Packaged and Shipped
How long can PCBA finished products be stored?
What Are the Differences and Relations Between PCB, PCBA, and SMT?
PCB Baking Specifications
PCB "Solder Mask Tenting" and "Solder Mask Opening"
Five reasons for PCB deformation and six solutions
Importance of first article inspection of PCBA board
Temperature zone standard for SMT reflow soldering
Small and medium volume PCB manufacturers in China
The main reason for PCBA cleaning
For power filter, the more capacitors, the better?
What does PCBA programming mean?
Content of PCB incoming testing
What conditions must be met for PCB circuit board soldering?
What is Blind via and Buried via
PCBA Manufacturers Temperature and Humidity Sensitive Components Management
Why choose Shenzhen SMT processing factory?
How long does it take to calculate the quotation for PCBA manufacturing?
Introduction of PCB design clearance requirements
Explanation of BOM, DIP, SMT, SMD
Introduction of the process of PCBA prototype
How to prevent pseudo soldering or cold soldering defects in PCBA manufacturing?
Factors that affect the Price of FPCB
What information is required for SMT processing at PCBA factory?
Skills of using 0ohm resistor in PCB design
How to select a PCBA manufacturer
SMT processing solder joint quality inspection
Characteristics difference between immersion gold PCB and gold plating PCB
Common malfunctions of Circuit Board Caused by Moisture
A Few Rules about PCB Panelization
Compare of multi-layer PCB with single/double layer PCB
Why do we need to introduce so many subdivided GND
Difference between immersion gold boards and gold plating boards
Aluminum PCB structure
Classification of different GND in circuit
Why PCB baking is necessary during manufacturing process
The handle and precautions of OSP board in SMT process
How to choose capacitors for filter decoupling
How to choose filter capacitor for switching power supply
5 database need for SMT process
Function of three-terminal capacitor
Introduction of PCB OSP surface treatment
Method of inspecting the quality of SMT by step
How to find the short point between VCC and GND
Difference between 850nm and 940nm infrared LED
Component layout of PCB SMT DFM
Pad shape influence on the strength and reliability of the soldering joints
The difference between high temperature solder paste and low temperature solder paste
Introduction to manual welding processing
Manual visual inspection in PCBA processing
Characteristics of the conformal coating process
Difference between hardware engineers and software engineers
PCBA processing operation rules
China PCB upstream materials has continued to soar
Difference between serial buses and parallel buses
The key points of quality control in PCBA processing
Common causes of solder beading during SMT process
Analysis of the advantages and disadvantages of HASL PCB surface
Requirements for layout of components during SMT assembly
Selection of electronic components and CCL for PCBA
Performance and appearance quality inspection of components.
Quality and Reliability of SMT Chip Processing and Production
Coupling and decoupling function of capacitor
Two methods to connect digital ground and analog ground
Common sense in SMT process

What Do Capacitive Coupling and Decoupling Mean?

Capacitors may be the most component in a circuit. SMD or Plug-in capacitors are densely placed on PCB! The role of the capacitor is filtering, bypass, coupling, decoupling, storing energy and so on. " Let the AC signal pass and block the DC signal" is the most basic function of capacitor. Today Shenzhen PCBA manufacturing factory SysPCB are going to talk about the functions of "coupling" and "decoupling" that are difficult to understand. Let's talk about the functions of these two.

1. Coupling

Capacitor has a coupling effect. We send the output signal of the front-end circuit to the back-end circuit, which is called coupling. Capacitance is a process of isolating DC and coupling AC. C2 and C3 in the picture below are capacitive coupling.


Coupling capacitor


What is used here is capacitive coupling. In this way, the DC operating points of the front-end and back-end do not affect each other! If C2 and C3 are directly connected, this is called direct coupling. Adding a capacitor is capacitive coupling. That is, the input AC signal is sent to the post-amplifier circuit through the capacitor for amplification, and the DC signal is isolated.

When the frequency is low, such as audio, the capacitor here may be replaced with a polar electrolytic capacitor. The negative pole is connected to the ground direction. Why use electrolytic capacitors? Because the capacity of electrolytic capacitors is larger, the capacity of non-polar capacitors is generally smaller.

By the way, C1 in the figure is a filter to filter out the noise of the input signal. R1, C1 form a resistance-capacitance filter.


2. Decoupling

What does decoupling mean? As mentioned earlier, coupling means that the signal is sent from the front-end to the back-end circuit. And decoupling, as the name implies, is to remove the useless signals that are coupled. Decoupling capacitors are generally placed at the output terminal of the power supply. As shown in the figure below, C27 is a decoupling capacitor. The value of its capacitance depends on the size of the interference signal coupled from the back-end circuit, that is, the load end.


Decoupling capacitor


For some reasons, at the load end, there will also be some majeure factors that cause voltage fluctuations. This voltage fluctuation will in turn affect the voltage of the power chip. This output capacitor decouples the voltage fluctuation coupled from the load end.

For example, when the load is running at full load, the current is very large. Sometimes there is no need to run at full load, the current will be small. At the conversion moment of high current and small current, the power chip will not have time to respond. And this decoupling capacitor works, and stabilizes the voltage fluctuations coupled from the load. Thus the power chip is not affected.