Do Thunderbolt monitors use the multiplexed DisplayPort signal?

A DisplayPort signal can be multiplexed onto a Thunderbolt cable. In fact, multiple DisplayPort signals (Intel Cactus Ridge 4C) can be multiplexed onto the same Thunderbolt cable.

Multiple Thunderbolt monitors may be daisy-chained on the same Thunderbolt cable, provided that the graphics card in the PC supports this.

However, a passive Thunderbolt to DisplayPort adapter may only be connected at the end of a Thunderbolt daisy-chain.

I'm confused as to how Thunderbolt monitors can be daisy-chained in light of the restriction on passive DisplayPort adapters above. Does each Thunderbolt monitor contain its own PCIe graphics card? Is there a special Thunderbolt to DisplayPort chip that can be daisy-chained to other devices?

Solution 1:

Thunderbolt 3 is a protocol based around Intel's Alpine Ridge controlles. These controllers take PCIe and DisplayPort signals and multiplex them down the same cable using the Thunderbolt 3 protocol.

For active Thunderbolt 3 devices, the AR controller acts as the demultiplexer whist also handling daisy chaining (each link is point to point and the controller routes packets between the two links). The demultiplexer can be used to isolate the DisplayPort data which can then be used by the display.

Passive adapters must be at the end of the chain because they have no AR controller and so lack the smarts to daisy chain the bus. To facilitate the passive adapters, Thunderbolt 3 has an alternate mode in which raw DisplayPort signals are sent down the cable. Once a thunderbolt link is in the alternate mode, further thunderbolt devices can't be connected as the signalling is no longer Thunderbolt.