How Much Impact Will PCB Right-angle Routing Have On Signal Transmission

Due to the rectangular go line, line width increase its impedance will decrease, so will produce certain signal reflection phenomenon, we can according to the impedance of the transmission line section mentioned in the formula to calculate the line width increasing after the equivalent impedance, and then according to the experience formula to calculate the reflection coefficient: rho = (Zs - Z0)/(Zs + Z0), usually rectangular walk line impedance changes caused by between 7% and 20%, and the reflection coefficient is 0.1.

Radio frequency, high speed digital circuit: avoid sharp angles and avoid right angles as much as possible.If it is a radio frequency line, if it is a right Angle at the corner, there will be discontinuity, and discontinuity will easily lead to the production of higher mode, which will affect the radiation and conductivity.If the RF signal line takes a right Angle, the effective line width at the corner will increase, and the impedance will be discontinuous, causing the signal reflection.

To reduce discontinuity, there are two ways to treat corners: cut corners and rounded corners.The radius of the arc Angle should be large enough, in general, to ensure that: R>3W.

In PCB routing rules, there is a "key signal line priority" principle, that is, power supply, simulation signal, high-speed signal, clock signal, differential signal and synchronization signal and other key signal priority routing.

The main characteristic of analog signal routing is its poor anti-interference, so the protection of analog signal should be considered when routing.The processing of analog signals is mainly reflected in the following aspects:

1. In order to increase its anti-interference ability, the wiring should be as short as possible.

2. The impedance control requirements can be abandoned for some analog signals, and the wiring can be appropriately bolded.

3. Limit the wiring area, and try to complete the wiring in the analog area, away from digital signals.

High-speed signal wiring requirements:

Multi-layer routing high-speed signal routing circuit is often high integration, routing density, the use of multi-layer is not only necessary for routing, but also an effective means to reduce interference.