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.
How to reduce the mutual interference between digital signals and analog signals?
(1) The design of the circuit schematic: The design of the circuit schematic is mainly the PROTEL099 schematic design system (AdvancedSchematic) to draw a circuit schematic. In this process, we should make full use of the various schematic drawing tools and various editing functions provided by PROTEL99 to achieve our goal, that is, to obtain a correct and exquisite circuit schematic.
In this article,I will tell you a new way to solve the problem of high speed singal pcb design
At present, in the manufacture of printed circuit boards, the wires are mostly copper wires. The physical properties of the copper metal itself determine that there must be a certain impedance in the conduction process. The inductance component in the wires affects the transmission of voltage signals. The composition affects the transmission of the current signal, and the influence of the inductance is particularly prominent in the high-frequency line.
Via is one of the important components of a multilayer PCB, and drilling costs typically account for 30% to 40% of PCB board costs.
Common impedance interference is caused by a large number of ground lines on the PCB. When two or more loops share a ground line, different loop currents generate a certain voltage drop on the common ground. This voltage drop will affect the circuit performance when amplified. When the current frequency is high, it will be very The large inductive reacts to the circuit.
The basic principle of CB cascading design: For PCB manufacturers, PCB cascading solutions need to consider many factors.
In SoC design, the coupling between signals can cause signal integrity problems. Neglecting signal integrity problems can lead to crosstalk between signals. Reliability, manufacturability and system performance will also be reduced. This article describes the design of ASIC chips. A method for solving signal integrity problems.
The frequency measurement is generally performed by a scanning spectrum analyzer, which scans the amplitude of each frequency signal and stores it under a certain resolution bandwidth (RBW), thereby displaying the information of the amplitude as a function of the entire frequency band. The RBW is an important consideration for scanning spectrum analyzers to provide excellent dynamic range and high accuracy of the static spectral components of the signal. However, the main disadvantage of a scanning spectrum analyzer is that it tests the amplitude of a frequency point of the signal only at one point in time.
Wireless signals are an integral part of many embedded systems today, and manufacturers of mobile terminals are discussing media convergence, where consumers can browse the web or watch the game in a notebook, mobile phone, portable digital TV or PDA.
Through the calculation and analysis of signal integrity to find the solution space of the design, and finally on the basis of the solution space to complete the PCB board design and verification.
As integrated circuit output switching speeds increase and PCB board density increases, signal integrity has become one of the issues that must be addressed in high-speed digital PCB design. Factors such as components and PCB boards, layout of components on the PCB, and wiring of high-speed signals can cause signal integrity problems, resulting in unstable system operation or even no work at all.
There are many simulation tools for analyzing signal integrity, each with its own characteristics.
For chip design, there are usually two ways to solve signal integrity problems. The RF solution focuses on the transmission line, often using impedance matching on the package boundary, while the digital (ie, broadband) solution emphasizes the choice of package, controlling the number of simultaneous switching and switching speed, and using between the external power supply pins of the package and ground. Bypass capacitors, the capacitance inside the IC is achieved by the overlap of the metal layers, which provides a local low-impedance path for high-speed transient currents to prevent ground bounce.
Signal Integrity is a state in which the signal is not damaged. It shows that the signal maintains its correct functional characteristics after transmission through the signal line. The signal can respond with correct timing and voltage in the circuit. It can be known from the timing of the IC if the signal is in steady state time (in order to correctly identify and process the data, The IC requires a large transition within the time period during which the input data remains unchanged before and after the clock edge, and the IC may misjudge or lose part of the data. If the signal has good signal integrity, the circuit has the correct timing relationship and signal amplitude, and the data will not be captured by mistake, which means that the receiver can obtain relatively pure data. Conversely, if a signal integrity fault such as false triggering, damped oscillation, overshoot, undershoot occurs, any signal transition will occur, causing the input distortion data to be sent into the latch or captured on the distorted clock edge. Data, the signal can not respond properly, resulting in abnormal system operation and performance degradation.
The earlier the signal integrity (SI) problem is solved, the more efficient the design is, so that the termination of the device is not added until the board design is complete. There are many tools and resources for SI design planning. This article explores the core issues of signal integrity and several methods for solving SI problems, ignoring the technical details of the design process.
Signal integrity issues have different ways of expressing them. The timing problem is always the first, and the shortening of the signal rise time and fall time will first cause timing problems in the designed system. Secondly, signal oscillation, signal overshoot and undershoot due to transmission line effects can pose a great threat to the fault tolerance and monotonicity of the design system. In slow systems, interconnect delays and signal oscillations are often overlooked by design engineers, primarily because signal sway caused by transmission line effects has sufficient time to stabilize in slow systems. However, as signal transitions continue to increase and system clock frequencies continue to increase, the time it takes for signals to travel between devices and prepare for clock timing is greatly reduced. The severity of the problem has suddenly increased and the likelihood of failure has increased rapidly.
Regarding signal integrity issues, when the system clock exceeds 50 MHz, the signal interconnect on the board introduces signal delays on the timing path, and these signal delays constrain the performance of the board-level design. How the transmission line effect will quickly introduce serious signal integrity issues like signal oscillation, overshoot and undershoot, and how these issues will threaten the noise tolerance of the design and the monotonic consistency principle of the design.
Such as skin effect and dielectric loss, effects of vias and connectors, differential signaling and routing considerations, power distribution and EMI control.
This article focuses on some of the signal integrity issues that PCB design needs to consider in gigabit device data transfers.
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