But why is it important? All in all, the end pocket that has to drive this is ours, the consumer. This is also driven by our need to process things faster. Faster data transfer, faster system boot time, faster internet, faster charging and on and on..The consumer electronics has swiftly transformed from what is known as a parallel architecture to a serial bus owing to the many benefits associated
with it. All the latest standards like USB, SATA, HDMI, Display Port , Thunder Bolt carry data on a serial bus from the port of product to the IC within. The serial bus consist of two copper lines called traces running in parallel to each other on Printed Circuit Board like a train rail connecting two stations. In this case, two pins from the connector of the product to two pins of the IC mounted on the PCB. Data travels between these points like a train traveling between two stations. To cater to our need to see quick transfers , the port speeds has been consistently increasing with a change in generation of standard in consideration.Let’s discuss few serial standards contained within the product and their usability in general from a connectivity perspective.
USB1 or Low Speed USB.
This is essentially a serial bus for connecting a mouse to the PC and runs at 1.5 Megabits per second that is about 1.5 Million bits/second.
USB1.1 or Full Speed USB.
This bus connects your keyboard to the PC and runs at 12Mbps.
Backward compatible with USB1 and USB1.1 runs at 480 Mbps and this bus is rightly termed as High Speed USB.
So what is backward compatibility? In simple terms the same USB2.0 port on your PC can connect to a pen drive running at 480Mbps, a keyboard at 12Mbps and a mouse at 1.5 Mbps.
Backward compatible with USB2.0, USB1.1 and USB1 and running at 5 Gigabits per second, that’s about 10 times faster than USB2.0.
So a USB3.0 port on your PC also known as a host port can be connected to a USB3.0 pen drive, USB2.0 Pen drive, USB1.1 Keyboard and USB1 Mouse. This backward compatibility is only true for host ports like that on a PC. However, a USB3.0 pen drive that is a device port would not connect with a USB2.0 Host port on the PC at 5Gbps.
Next comes USB3.1
Host Port is backward compatible and can be connected with USB3.0, USB2.0 and USB1.1 devices and has a data rate of 10Gbps.
However a USB3.1 device might not connect with a USB3.0 port at 10Gbps.
And the ubiquitous USB C Port.
The beauty of USB C is the small sized connector yet with higher number of pins in the connector with multiple serial lanes, resulting in an overall increase in speeds up to 10Gbps while also catering to providing a higher wattage of power up to 100 Watts at 20 Volts to devices. The multiple serial lanes can also carry HDMI and Display Port Signals and USB C is backward compatible with all USB standards with additional adapters making it truly ubiquitous.
Carry all video and audio on serial copper lanes. HDMI does exactly that. But what’s evolving the standard? The need of picture clarity and color has increased the pixel quantity and resolution of the display. Higher the Display (usually termed as HDMI Sink) pixels and higher the resolution, higher is the amount of data that need to be transferred from any HDMI Source to that Display sink. And why not? In practical terms, you would clearly see the difference between VGA and HDMI as HDMI carries much more Mbps per second compared to VGA making the picture quality much clear and crisper. Given an option to connect VGA or HDMI, always choose HDMI for a better visual experience.
How does HDMI do it?
HDMI carries three pairs of data lanes each at a specific frequency all adding up to a much higher rate and all synchronized to a single clock pair. So your HDMI connector has multiple serial data pairs and a clock pair along with Power and Ground pins connected to the Printed Circuit Board of the product in discussion.
So let’s look at different speeds, HDMI caters to and start with the minimum ones contained in any product now a days.
The clock speed that we discussed above is driven at 340 MHz and 10 bits of data per serial lane is transferred at 340 MHz making the overall speed per lane at 3400Mbps. This multiplied by three pairs make it a total of 10.2 Gbps of data transfer between Source and Sink. This enables to carry 3D data and much deeper color bit per pixel as required by the sink Display. To make it simple, we’ve left out the 8b/10b encoding overhead applied to 10.2 Gbps, making the overall data at about 8Gbps.
The clock speed now increases to 600 MHz and 10 bits of data per serial lane is transferred at 600 MHz making the overall speed per lane at 6000Mbps that is 6Gbps. This multiplied by three pairs make it a total of 18 Gbps of data transfer between Source and Sink. This enables to carry 3D data at 60Hz and much deeper color bit per pixel as required by the sink Display.
Display that is Sink device specs need to be looked into before arriving at any conclusion. 4K X 2K display resolution at 60 Hz usually goes well with HDMI 2.0. It’s good to have HDMI 2.0 on your Source Product, but does the Display device support HDMI 2.0 is what is to be addressed before arriving at a decision. Another key thing is the interface connector itself, that can range from HDMI-A to HDMI-E and can be a Micro or a Mini HDMI form factor.
The new age gamers should look at the coming up standard HDMI2.1 that would enable 4K X 2K, 8K and higher resolution with higher refresh rates up to 120 Hz.
Display Port Connectivity
Display Port also carries Audio and Video signals on Serial Lanes with different frequencies and data rate as compared to HDMI Standards.There are up to four pair of serial data lanes and a pair of serial clock lane. The relevant product in consideration usually has one of the HDMI or Display Ports that let’s you connect to the Display Device with a cable. So, let’s see the different standards Display Port caters to
Display Port 1.1 to Display Port 1.4
DP1.1 is the is the early standard of Display Port and with 10 bits being transmitted per lane at a clock frequency of 162 MHz giving it a overall bandwidth of 1.62 GHz
and an effective data rate of 1.29Gbps.
DP1.2 runs a maximum of 4 data lanes each at a clock frequency of 270MHz transmitting 10 bits, giving it a Bandwidth of 2.7 Gbps per lane , overall Bandwidth of 10.8 Gbps and effective Bandwidth of 8.64 Gbps.
DP1.2a is an upgraded version of DP1.2 with a clock frequency of 540MHz and a bandwidth of 5.4Gbps per lane that is a total Bandwidth 21.6 Gbps and an effective bandwidth of 17.28 Gbps. after relevant encoding/decoding schemes ( 8b/10b).
DP1.3 runs a maximum of 4 data lanes each at a clock frequency of 810MHz transmitting 10 bits, giving it a Bandwidth of 8.1 Gbps per lane , overall Bandwidth of 32.4 Gbps and effective Bandwidth of 25.92 Gbps. This Bandwidth is enough to support a 4K UHD (3840×2160) Display at 60Hz.
DP1.4 supports 8K UHD (7680×4320) with 10 bit color and HDR at 60Hz or 4K HDR at 120Hz applying compression techniques unlike DP1.3. The overall Bandwidth still remains at 32.4Gbps and effective Bandwidth at 25.92 Gbps. Compare this with HDMI 2.0 up to 18Gbps and HDMI2.1 up to 48 Gbps.
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