Overclock.net › Forums › Components › Monitors and Displays › Looking for help making 4K UHD @120Hz happen (LVDS/FPD-link specific)
New Posts  All Forums:Forum Nav:

Looking for help making 4K UHD @120Hz happen (LVDS/FPD-link specific)

post #1 of 4
Thread Starter 
I'm currently attempting to get my 4K UHD panel working @ 120Hz refresh rates the panel in question is this one

The panel uses 20 LVDS pairs more specifically it uses 4 channels with 5 LVDS pairs each it also if I'm reading the datasheet correctly has an option for Side by side image by giving 2 channels to the left and 2 to the right just as we've seen with the Sharp IGZO 4K UHD screens.

I've contacted various companies first 3 Dutch companies which either redirected me to someone else who might be able to get it done ending me up with a estimate quote of 30k models @ 200 euro each the model to get the costs out (that was FPGA based though)

So what is keeping us from our goal?
  1. HDMI bandwidth limitations since HDMI is currently limited to 340MHz pixel clock.
  2. Tcon limitations
  3. Limited bandwidth to the panel

Possible fixes:
  1. We can use a different connector dual link DVI seems to be the best choice (But DP and HDMI 2.0 are also viable)
  2. Instead of using a single Tcon board we use multipe 2 for now no need to overcomplicate yet (This is a very viable solution with one thing setting us back that is that it will try to drive the entire panel and since you can't set eyefinity or suround to only output stripes of the entire screen )
  3. This is a head breaker but it might be possible to push more over the LVDS pairs.

Pretty much all the discussion about it is here http://hardforum.com/showthread.php?t=1756171&page=17

There are high end timing controllers as the one I mentioned in the last page that power today's 120Hz 1440P monitors.
Those can do 450MHz according to specs and use 10 bit 4 channel link too, It would be able to do 60Hz at 4K UHD with a small OC. (which would pretty much overrule the argument that Sharp and Asus use about there not being a transmitter that can do it available though they are right about the not in specification part)

Some more info on the high quality dual link DVI receiver and timing controller.
Edited by maarten12100 - 8/14/13 at 10:54am
post #2 of 4
As a LVDS display interface designer , I can say that current LVDS technology (FPD-link) is pretty much limitted to 170Mhz pixel clock. Data is serialized 7x so we are looking at 1.2 Gb/s with a clock provided separatly. (not embedded).
To achieve such bandwidth, the data/clock skew need to be well managed. Here we are talking about +/-250ps margin knowing that 1mm extra cable burns 100ps skew.
V-trans Microelectronics offers such IPs (FPD-link with automatic skew compensation) to be embedded in SOC.

Other providers just move to serial links V-by-one HS, internal DisplayPort, HDwire , etc ...
but for LVDS, one can still use it. Dual link offers up to 340Mhz, Quad link up to 680Mhz, ie ~600Mhz 30-bit for 4Kx2K 60Hz.
For 4Kx2K @ 120Hz, one would need 8 links , where 1 link is (5 data +1 clk ) LVDS pairs.

Rem : each link need its own clk pair, to allow skew between links, making the system possible.

post #3 of 4
I hate to be a killjoy, but is there any use in getting 4K to 120Hz? The cost of GPUs to drive 4K 120Hz would be horrendous.

But I really do like the idea of getting "enthusiast" monitors made, so I offer another idea: 1440p Super AMOLED+ 120Hz. I don't know much, but if the colour and longevity issues have been sorted out this monitor would be just amazing. And best of all it wouldn't break the bank to get good fps.

Either way I'll definitely be following this thread to see what you can achieve.

Edit: if the controller PCB you mention is the same as in my X-Star, then those show massive colour shift above 450MHz. It may be better to go all out and see how much it would cost to have custom PCBs capable of 500MHz+ made, and what kind of cable would be required for that much bandwith.
Edited by Moragg - 9/24/13 at 1:46am
post #4 of 4
Thread Starter 
I've been looking into VX1 there seem to be no reference boards only fpgas but the chips are there also there are fpd link to VX1
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Monitors and Displays
Overclock.net › Forums › Components › Monitors and Displays › Looking for help making 4K UHD @120Hz happen (LVDS/FPD-link specific)