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2-2151560-2_TE Connectivity_Crimpers, Applicators, Presses

来源:LM317 Electronics Components编辑:TDK时间:2021-06-15 14:31:03

A taxonomy of jobsAlthough signal integrity work is key, the job of high-speed interconnect engineering involves a matrix of roles that are often played in concert by many engineers, according to Charles Byers, a senior fellow at Lucent Technologies. There are several subdisciplines involved,” Byers said.

When there is a failure in one power path, the full load of the server is transferred to the remaining power feed. This causes the load on that power feed to double. For this reason, the AC mains branch circuits feeding the equipment in a dual path system must always be loaded to less than ½ rated load, so they have the capacity to take over the complete load if they are required to.

Ensuring that a branch circuit is loaded to less than 50% of its rating is a task made more difficult when the loads exhibit dynamic power consumption. A system may be tested upon installation and be found to have branch circuits operating below 50% rating, and then at some future time of high computational load the system may be operating at greater than 50% rating.

2-2151560-2_TE Connectivity_Crimpers, Applicators, Presses

If the branch circuit in a dual path system enters the condition where the load is over 50% of the branch rating, then the redundancy of the system is lost. If one feed were to fail, the second feed would then be immediately overloaded and the breaker would be likely to trip as described in the previous section. Again, since it is happening at a time of high computational load, it is likely that the computing equipment is handling a large number of transactions so the loss of redundancy is very likely to be occurring at a particularly undesirable time.

Masking of the problem

The equipment that exhibits dynamic power consumption may represent only a small fraction of the total power consumption of a data center or network room. If 5% of the equipment in a data center has a dynamic power variation of 2-to-1 and the rest of the equipment draws constant power, then bulk power measurements of the data center at the main power feed or at a Power Distribution Unit might only vary 2.5%. This might cause an operator to believe that no significant dynamic power variation problem is occurring when in reality a significant risk of breaker tripping, overheating, or loss of redundancy may be occurring. Therefore, there is a very real possibility that the problem may exist yet be unrecognized by experienced operators.

2-2151560-2_TE Connectivity_Crimpers, Applicators, Presses

Managing dynamic power variation

To mitigate against the problems described in the previous sections, designers and managers of data centers and network rooms must adapt to the new realities of dynamic power consumption. There are a number of means that can be used to accomplish this, and some are reviewed as follows:

2-2151560-2_TE Connectivity_Crimpers, Applicators, Presses

Separate branch circuit for each server

If a separate branch circuit is provided to each server, then branch circuit overload cannot occur. This is true because every server is assured to operate from a dedicated branch circuit by design. This solves the issue of branch circuit overload and solves the problem of loss of redundancy. It does not solve the thermal problems, but these are typically not the largest risk. However, this is a very complex and expensive solution where small servers are deployed such as 1U or 2U servers since this could require an extremely high number of branch circuits per rack. In the extreme case, a rack filled with dual corded 1U servers could require 84 branch circuits, which corresponds to two large circuit breaker panel boards. This solution is more practical when larger servers or blade servers are used.

Most interesting, however, is the ability of CMOS assistance to improve the performance of pipelined and bandpass delta-sigma A/Ds. This is an area of study that may enable cost-effective direct RF sampling.

While optimizing individual blocks in terms of power consumption and space is one route to mitigating the impact of multiple RF chains, two other paths exist to achieve that optimization. The first is the reuse of power-hungry portions of the chain such as the local oscillator. Intel has already achieved ranges of 1.8 to 5.8 GHz in CMOS.

The other route is to replace the front-end preselect filters with RF microelectromechanical systems. The MEMS use the electrically controlled movement of a cantilevered arm to modify the values of capacitive and inductive filter components . They can also be used to change the matching for antennas. The devices can change the characteristics of a filter within a millisecond and have the additional advantage of being almost a perfect wire, so there are no losses associated with them.

Reliability remains a question, as do bulk and cost. Nonetheless, many researchers are confident that MEMS are one of the keys to unlocking agile RF front ends.

Continuously flexed screens would be rolled and unrolled repeatedly as a display scroll.

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