What is LVDS Technology, LVDS is a low-amplitude differential signaling technique that uses very low amplitude signals (approximately 350mV), as electronic board design techniques continue to advance, interconnects of higher rate signals are required. In the case that the digital parallel signal of the digital synchronous signal is to reach the limit, the advantages of LVDS, such as large signal-to-noise ratio, low voltage, low power consumption, and high-speed transmission are more and more favor by design engineer from board levels and systems.
Data is transmitted over a pair of differential PCB traces or balanced cables that can transmit serial data at speeds of up to thousands of Mbps. LVDS operates in a current-driven differential signaling mode with a maximum transmission distance of more than 10 meters. In order to ensure that the signal is not affected by the reflected signal when it propagates through the transmission line, the LVDS signal requires the transmission line impedance to be controlled, where the single line impedance is 50 ohms and the differential impedance is 100 ohms.
In practical applications, some high-speed digital circuit design simulation analysis tools are used to adjust the line width and line spacing of the traces by reasonable setting of the stack thickness and medium parameters, and calculate the single line and differential impedance results to achieve the purpose of impedance control. But in many cases, it is more difficult to satisfy both single-line impedance and differential impedance.
On the one hand, the adjustment range of the line width and the line spacing is limited by the physical design space, for example, the wiring and line width in the BGA or in-line type edge connector are limited by the pad size and spacing, on the other hand, the line width and Changes in line spacing affect the results of single line and differential impedance. Therefore, under certain stacking conditions, understanding the relationship between line width and line spacing and impedance makes it very meaningful to set the differential routing rules for designers.
