Signal Integrity: end-to-end Topology

In actual situations, the network topology also has a significant impact on signal integrity. The network topology includes point-to-point, point-to-point, chrysanthemum link, T-shaped topology, and star topology. For different network topologies, we recommend that you use the following method:

1. Point-to-point (a): The Source end can be connected in series and the terminal can be matched in parallel. The parallel impedance of the terminal should be equal to the characteristic impedance of the transmission limit line, and the serial impedance of the source end is equal to the difference between the characteristic impedance and the internal resistance of the drive, which is the simplest layout.

2. Point-to-point multi-point (B): Because the sub is short, the impedance of the cross-line end of the destination end is equal to the characteristic impedance of the transmission line.

3. Chrysanthemum Link (c): this is a general topology and is often used in multi-branch bus, such as the front-side bus and memory bus of a PC. The main drawback is that the intermediate device must be connected to the backbone of the bus using a short line. It is best to place the loads evenly in the chrysanthemum link topology. The Chrysanthemum link is only connected to the final end, and its size is equal to the characteristic impedance of the transmission line.

4. T-shaped topology (d): The T-type topology is usually single-threaded, that is, there is only one driving source in the topology, and the clock usually uses the T-type topology, as mentioned above, symmetry is essential for obtaining good signal integrity. In the T-shaped topology, as long as the wire length between each receiver and the T-point is equal, this topology is balanced for the drive. Because the T-type topology forks signals at the T-point, the source end looks equal to two transmission lines in parallel, so the transmission line impedance value between the T-point and the receiver should be twice the impedance value of the basic transmission line, the impedance of each branch is twice that of the basic transmission line.

5. star topology (e): When wiring a star topology, the transmission line distance between each device and the Public point must be roughly the same to ensure that each load is equal. In a star topology, no matter which device acts as the driving source, this topology is symmetric. The electrical impedance of the star topology is the same as that of the transmission line.