The High Definition TV “experience” continues to drive manufacturers to offer truly digital devices. The days of analog video interfaces are limited. In previous articles, we touched on HDMI connections. It is clear that HD sources such as DVD players, Cable settop boxes, satellite boxes are transitioning to the HDMI standard. It is inevitable that future HD sources such as HD DVD players (HD or Blue Ray), and PlayStation 3 will utilize HDMI as the interface standard. With all these new HDMI source, how does one get the desired input to the HD monitor? In this article, we will get into the details of such a device: the HDMI
What is a HDMI
Why do I need a HDMI
What features do I look for in a HDMI
– Expandability: 4 ports devices are recommended for future expandability. If you use a 2 port, then you have no expandability. It is likely that future HD sources such as games stations, HD DVD player/recorders will utilize HDMI.
– HDCP transparancy: any
– Backward compatibility with DVI-D: There is a mix of both HDMI and DVI-D devices in the field. Users should select a HDMI
– Remote control: A remote control to select the desired channel is essential.
Design consideration of a HDMI
HDMI is extremely high speed digital transmission standard with an aggregate data rate of ~4.95 Gbps. Jean Baptiste Fourier (1768-1830) showed that any signal waveform can be resolved into a summation of harmonically related sine waves. The amplitude of the sine waves can be determined by calculation of Fourier transforms.
So what in the word does some dead French mathematician have to do with the HDMI
As data rates increase, every aspect of the
HDMI is based on a 100 ohm (differential) impedance. It is imperative that the
Minimum Insertion Loss:
Signal loss should be minimized in order to maximize signal integrity to the output of the HDMI
Minimum Cross Talk:
With multiple inputs (up to 4), all potentially being active at same time, it is imperative that the desired channel not be interfered from any undesired channels. Again, careful RF microwave design techniques minimize cross talk.