How PCB Assembly China Manufacturer Design PCB Analog Circuit?Posted on 2020-02-18
Very simple guide to understand different types of analog printed circuit board
Table of contents:
1-Introduction to Pcb Assembly China
3-Brief description of Pcb Amplifier Types
4-Pcb Assembly china High-frequency Amplifier
5-What are the basic rules for designing analog PCB?
6-What problems pcb assembly china face in designing digital PCB?
7-instructions for high-frequency PCB circuit
Introduction to Pcb Assembly China
Pcb assembly china companies are manufacturing analog circuit signals for more than 60 % of electric devices. A PCB is a crucial part of any electronic gadget for tiny devices or complex computers. Its complex interconnect components include resistors, diodes, capacitors, etc., enabling the devices to work in series. generally, a printed circuit board works as a soul of any electrical component. it is very importantly, so the PCB assembly process should be error-free and requires attention to common mistakes in assembly making process. Here are some factors to note:
Pcb Assembly China Basis rules for designing
There are three basic thoughts for designing rules.
- Component placement
- Signal conductor
- Supply and ground line conductors
In analog circuit design, component placement has significant role.
Following are the pcb component placement guideline:
- Front panel components should have proper alignment.
- Internal components must have a board edge placement
- Metal case components should be far from internal components.
- Heat sensitive and heat-producing components should not have side by side placement. Therefore proper planning must be there for the arrangement of both. The heat-producing components should be arranged all over the board evenly to avoid overheating and the heat-sensitive components must be placed with appropriate space from them.
- Similarly, mounting screws, it is necessary to have proper space between nuts and washer and there must not be any conductive track beneath this.
Signal conductor instructions for Pcb Assembly China
Reference level, feedback, input, output, etc. are some important tasks for pcb assembly china. Moreover, the signal conductor has to be short as possible for all analog circuit design. The signal conductor for the following circuits should have an adequate formation.
- High gain DC Amplifier
- Differential Amplifier
- Low-level signal Amplifier
- High-frequency Amplifier
- Multi-stage Amplifier
Brief description of Pcb Amplifier Types
- High gain DC Amplifier
Generally, Pcb assembly china uses this device to amplify low-level signals. You can easily form a thermocouple junction between lead and copper. This thermocouple junction forms different voltages which cause noise signals. A pcb manufacturer should place the input stage in a separate edge to keep the temperature stable.
- Differential Amplifier
The Differential Amplifier is important as it moves between tow signals and dismisses the common voltage. If the differential amplifier or PCB design is not proper and the level of the signal is low then the common voltage creates a small difference signal. The geometrical symmetry while designing the amplifier must be correct otherwise the unbalanced impedance can disturb the performance of the circuit. Similarly, the leakage resistance creates unbalance voltage. Moreover, the guard conductor connects the signal conductor to the guard of the equipment. This method helps in handling differential signals at a low level. Furthermore, the glass epoxy base for differential amplifier helps in minimizing the leakage problem.
Pcb Assembly china High-frequency Amplifier
Inappropriate PCB layout of high-frequency layout results lessens the bandwidth of the amplifier. The closeness of the ground and signal conductor results in high capacitance, which acts as a low filter pass filter, which reduces the bandwidth of the amplifier. Moreover, the closeness of output and input conductors result in vibrations. According to leading pcb assembly china manufacturer, the frequency of more than 10 MHz will cause vibration. But the amplifier will not oscillate when the desired frequency is given. The capacitive coupling between signal lines cause such problems. Thus the capacitive coupling should be less while making PCB design.
Supply and Ground Conductors
The power supply must have enough thickness to keep the resistance and inductance low. But the conductance is directly proportional to thickness or width. If analog and digital circuits are on the same PCB then they must have their own separate ground conductors. For reference voltage circuits, the supply lines must attach to input and the ground line must attach to the stable ground reference. Subsequently, stable ground reference is sensitive to the changes in ground potential. Simultaneously, the ground conductors have resistance, inductance, the doubtful current which causes voltage drops when passes from the ground impedance.
What are the basic rules for designing analog PCB?
Pcb assembly china states general rules for designing analog PCB circuit areas;
- To control the voltage drop through conductors and electromagnetic interference keep the signal paths short.
- Similarly, the analog and digital grounds on the same board should be placed separately.
- Connect the signal ground to the earth ground.
- Give a return path to the noise source by connecting the capacitive shields.
- The material of the magnetic shields should be highly permeable
- Furthermore, the metal used on the circuits have a proper arrangement and must not be moving
- the system should be stable so the common-mode signals will not distinct
- The bandwidth of the system should be according to the signal bandwidth requirement.
- Make the path of the loops according to the passage of current.
- Above all to control or upgrade the noise rejection between two PCB, use a pair of cable and twist them along.
What problems pcb assembly china face in designing digital PCB?
The demand for PCB in digital circuits is very much because of its performance but the knowledge of electronic transmission lines is also important.
If the design of digital PCB is not proper it may cause following problems for pcb assembly china manufacturer like
- Convert one pulse into two or more (double pulsing) which is known as Reflection.
- Produce delay signals
- Interrupt the signals known as Cross-talk.
- Can produce ground and supply signal noise
- Cause of electromagnetic interference.
What are the guidelines for pcb assembly china manufacturer for high-frequency PCB circuit design?
Following are the instructions for high-frequency PCB circuit
- For ground conductors, pcb assembly china manufacturer uses a large ground surface
- The wide power supply conductors are used
- Furthermore, ground and power supply lines must be parallel and close to each other
- The ground and power supply must have a decoupling capacitor in between
- The length of the conductor for a fast pulse should be kept small because the dielectric loss is directly proportional to length.
- Moreover, the dielectric loss is very important in the PCB however a PCB with proper high-frequency dimension should be used
- Designing the layout of the conductor is according to the capacitor and inductor. The more harmful element must not be used
- The lines should be kept small or the increase in the rise time must be as high as 1 sec/cm
- Prepare ground line via capacitor even the parasitic capacitance has a worse result.