Impedance control for PCB, when you are ready for PCB proofing, could you online order system in plate factory or seen in PCB board system documents, to do the impedance control for PCB
PCB impedance control for many beginner high-speed PCB design Layout of the bacteria causing confusion, but also any high-speed PCB Leo bacteria have to know, is also a lot of EDA technology BBS and EDA design magazine into the topic of discussion.
PCB transmission line impedance control hard?
For PCB design bacteria, the theory is not difficult, as long as you in the design documents identified those who walk how many characteristic impedance line needs to be done with respect to OK, plate factory just do according to your request, take responsibility.
But in reality, the impedance control is challenging, both plate factory and PCB design, must want to rely on his teammates, close communication, to avoid all kinds of pit.
In the early days of electronic products, the processor speed is not fast, external interconnected system transmission rate is relatively low, at this point, the PCB is a kind of carrier of the electronic component assembly and components of interconnectivity load board, therefore, go line is based solely on conduction of PCB as a starting point, the design and quality control as long as has the concept of direct current (dc) and alternating current (ac).
In recent years, with the rapid development of all kinds of multimedia applications, the processor speed faster and faster, external interconnection bus transfer rate is becoming more and more high, when we in the Layout of PCB wiring should consider the relative concept of square wave propagation of electromagnetic wave, and gradually transforms the original simple copper foil line, high speed,
Logic frequency LF)
With the high frequency (
Radio frequency RF)
Use of complex preach data line.
The characteristic impedance is also called the 'characteristic impedance.
Refers to under a certain frequency, transmission line (
Namely we make circuit board copper wire)
, relative to a reference layer (
Is often said that the shielding layer, mapping layer or reference)
, in the process of the electromagnetic wave propagation in the high frequency signal or call it the characteristic impedance of resistance, it is actually electrical impedance, electrical impedance, a vector sum, such as electric capacitive reactance.
PCB in electronic products not only current conduction effect, but also act as signals;
Electronics of high frequency, high speed, the PCB is required to provide the circuit performance must ensure that the signal reflection does not occur in the process of transmission, maintain signal integrity, not distortion;
The characteristic impedance is the core of the signal integrity problems;
Electronic equipment (
Such as computers, communications, switches, etc. )
Operation, the driving element (
Signals, signal lines to receive by PCB components (
In order to guarantee the signal integrity, demanding PCB line characteristic impedance (
Head and tail element must match the impedance matching;
A simple chestnuts, you are very spacious, roads standard high highway to 120 yards in a hurricane, then suddenly suddenly appeared in front of deceleration zone, the picture you to imagine it, but if you are driving a tractor in the village, at the rate of twenty or thirty yards in crawl, let alone met a speed bump, even a large puddle, gets him all the same.
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