Here you'll find insights into PCB design, tech trends, assembly issues, and trending topics
in the general news media as they relate to printed circuit board technology.
As experts in the manufacture and assembly of printed circuit boards, we work to make our blog a helpful resource on PCB topics and the industries that we work with, including automotive, consumer electronics, aerospace and many more.
26. When there are multiple digital/analog function blocks in a PCB board, the conventional practice is to separate the digital/analog grounds. What are the reasons?
Can you introduce some foreign technical books and materials on high-speed PCB design?
1. How to choose PCB board?
Each VXI bus device has a set of “configuration registers”. The system main controller reads some of the basic configuration information of the VXI bus device by reading the contents of these registers, such as device type, model, manufacturer, and address space (A16, A24). , A32) and the required storage space.
With the development of modern wireless communication systems, communication systems such as mobile communication, radar, and satellite communication have higher requirements on the switching speed, power capacity, and integration of the transceiver switch. Therefore, research on VXI bus technology and development meets the military. The special requirements of the VXI bus module is of great significance. We will use the virtual instrument idea to implement the hardware circuit in software. The RF switch designed below can be directly controlled by the computer, which can be easily connected with the VXI bus test system. Integration, to maximize the use of computer and microelectronics technology in today's testing field, has broad prospects for development.
PCB interconnect design techniques include testing, simulation, and various related standards, where testing is the method and means to verify the results of various simulation analyses. Excellent test methods and means are necessary to ensure the analysis of PCB interconnection design. For traditional signal waveform testing, the main focus should be on the length of the probe leads to avoid unnecessary noise introduced by Pigtail. This article focuses on new applications and development of interconnect testing techniques.
High-speed and high-density has gradually become one of the significant development trends of many modern electronic products. High-speed and high-density PCB design technology has become an important research field.
The interconnection of the board system includes: chip-to-board, interconnection within the PCB, and three types of interconnections between the PCB and external devices. In the RF design, one of the main problems facing the electromagnetic characteristics engineering design at the interconnection point, this paper introduces the various techniques of the above three types of interconnection design, including the device installation method, wiring isolation and measures to reduce lead inductance.
Since SMT generally uses infrared furnace heat flow welding to achieve component soldering, the layout of the components affects the quality of the solder joints, which in turn affects the yield of the product. For the design of RF circuit PCB, electromagnetic compatibility requires that each circuit module does not generate electromagnetic radiation as much as possible, and has certain anti-electromagnetic interference capability. Therefore, the layout of components directly affects the interference and anti-interference ability of the circuit itself. This is also directly related to the performance of the designed circuit.
With the development of communication technology, handheld wireless RF circuit technology is used more and more widely, such as: wireless pager, mobile phone, wireless PDA, etc., the performance indicators of the RF circuit directly affect the quality of the entire product. One of the biggest features of these handheld products is miniaturization, and miniaturization means that the density of components is large, which makes the mutual interference of components (including SMD, SMC, die, etc.) very prominent.
In the design of electronic systems, in order to avoid detours and save time, the anti-interference requirements should be fully considered and avoided, and remedial measures against interference should be avoided after the design is completed. There are three basic elements that form interference:
Although the current EDA tools are very powerful, as PCB size requirements become smaller and the device density becomes higher and higher, PCB design is not difficult.
Abstract: This paper systematically analyzes the various forms of power supply noise interference in high-frequency PCB boards and their causes. Through formula derivation and engineering experience, several corresponding countermeasures are proposed. Finally, the suppression of power supply noise should be followed. The general principle.
In high-speed PCB digital circuit systems, impedance mismatch on the transmission line will cause signal reflection and signal distortion such as overshoot, undershoot and ringing, and when the delay TD of the transmission line is greater than 20% of the signal rise time RT, the reflection The impact can't be ignored, or it will bring signal integrity problems. The method of reducing the reflection is: matching the source impedance with the transmission line impedance according to the characteristic impedance of the transmission line at the driving end thereof, or matching the load impedance with the transmission line impedance at the receiving end, so that the source reflection coefficient or the load reflection coefficient is zero.
Design of the material composition of the board
The manufacture of high frequency printed circuit boards is very important for the choice of substrate materials. When choosing a substrate material, you should pay attention to the following four principles.
The current worldwide demand for environmental protection has made electronic products more demanding in the miniaturization of the Ministry of Energy. This has also spurred the advancement of high-speed and large-capacity electronic products for data and information processing. On the other hand, IT products that are personally demanded are also moving toward functional integration, high-performance (high-speed), and low-consumption power. In the signal transmission mode of electronic products, the parallel transmission mode develops toward a continuous mode. And the way in which optical transmissions have been added to electrical transmissions has begun to emerge. The high integration and high frequency development of electronic components has led to a continuous increase in the demand for high-frequency printed circuit boards.
(1) Cross circuit is not allowed in the printed circuit. For the lines that may cross, it can be solved by “drilling” or “winding”. That is, let a certain lead be "drilled" from the gap under other resistors, capacitors, and triodes, or "wrap" from one end of a lead that may cross. How to make the circuit complicated in special cases, to simplify the design It is allowed to bridge the wires to solve the cross circuit problem.
The high-speed PCB layout technology driven by electrical rules realizes the design strategy of signal crosstalk control.