What does FPD-link stand for?

The term “FPD-link” refers to a video interface developed by Texas instruments (TI) which enables serial data transmission in vehicle applications. It is the abbreviation for “Flat Panel Display Link” and is also frequently used in laptops, flat screens or LCD televisions. With this point-to-point interface, the graphics processor output is connected to the display. The video signal cables routed in parallel are serialized in the transmitter chip and deserialized again in the receiver chip. This is known as a SerDes connection.

Who are the chip manufacturers for this?

Originally, FPD-link was developed by the chip manufacturer, National Semiconductors, in 1996. This company’s headquarters were based in Santa Clara, California. In the fall of 2011, it was taken over by Texas Instruments. Texas Instruments Incorporated, often also referred to as TI, is one of America’s largest technology companies, with headquarters based in Dallas, Texas. The company’s European headquarters are based in the Upper Bavarian town of Friesing. TI is one of the largest semiconductor manufacturers in the world. FPD-link is an open standard and can be used without a license. One of several interfaces that can be operated with FPD-link is FlatLink by Texas instruments.

What are its applications in vehicles?

FPD-link enables the transmission of high-resolution digital video content from one point to another. This is required for display and camera interfaces.

How was FPD-link introduced into cars?

FPD-link was the first large-scale interface with LVDS protocol where electromagnetic compatibility is improved by differential transmission. With LVDS, the three color signals are transmitted serially as three differential signals over three twisted pairs of conductors. A fourth pair of conductors transmits the clock signal. For higher color resolutions, FPD link can also be implemented over four wire pairs. Further development of FPD-Link led to FPD-Link II in 2006, which was specially developed for infotainment in automotive technology and for digital cameras. In this version, the clock signal is embedded in the color signals. This means that the RGB signal and the clock signal are transmitted via a single twisted pair of conductors. The interface becomes more compact and simpler. With the development of a suitable interface by Rosenberger, it also went into series production in 2006. The third version, FPD-Link III, was introduced in 2010. This differs from FPD-Link II in that bidirectional communication is handled via the same transmission channel. Control signals are transmitted via this link. It is even possible to operate two 4K UHD screens with FPD-Link IV.

Is LVDS used?

As an additional new feature, FPD-Link III stops using LVDS technology and uses only CML for the serialized high-speed signals. This enables it to easily work at data rates greater than 3 Gbit/s on cables longer than 10 m. CML technology works well when driving the single conductor in coaxial cables. As coaxial cables can control impedance and noise very well, they reduce the need for differential signals which means that impedance discontinuities and noise disturbances are better tolerated.

Is it possible to compensate for cable influences?

In the deserializer, FPD-Link III contains an integrated adaptive equalizer. The input signal for the deserializer usually has reduced integrity. This usually results from intersymbol interference (ISI due to cable loss. The adaptive equalizer can capture the poor signal and restore the original integrity. This function is useful in any application in which the cable can vary in length, operating temperature and humidity, as these variables influence the ISI that results from the cable’s low-pass filter effect.

Christian Neulinger

Christian Neulinger is "Manager Radio Frequency & Simulation" and has more than 10 years of professional experience in the development and qualification of innovative electrical components for wired high-speed data transmission. As an active member of various standardization committees such as IEEE 802.3, he is involved in the development of new high-performance data transmission systems for the automotive industry.