Beckman

<p>– Industry-specific research and development.</p>

The amount of power the reader needs to receive is also complex and depends on a number of details of implementation we shall consider somewhat more thoroughly in Chapter 4.For the present purposes, we shall suggest a plausible and convenient lower limit of around-75 dBm (0.03 nW), deferring justification of this value until later. With the reader's indulgence, we shall proceed to use these unjustified assumptions to construct a diagram of the reverse link power in the same fashion as that previously constructed for the forward link; the result is depicted in Figure 3.23 . We construct a second line like the first but starting at 5 dB less than the tag received power. Note that in this case, as the line descends, we are physically moving back towards the reader. If we move back 3 m (to intercept the dotted vertical line labeled 'forward-link-limited range'), we find the reader receives about -55 dBm, about 20 dB in excess of the power required by the reader's receiver. In fact, a receiver could be an additional 29 m away before the signal would fall so low as to fail to be received for this threshold value.

High-speed trace impedance ESD diodes also affect trace impedance when the edge of the signal passes the ESD component resulting in a lower impedance for both single-ended and differential high-speed traces.

Figure 6 shows the effect on trace impedance when a fast edge (200ps specified for HDMI) travels through the ESD diode. The simulation circuit has no termination, which results in a waveform step response.

NAC3FCA_Datasheet PDF

Figure 6: ESD circuit Impedance simulation waveform

This waveform will not settle to the 1.0V drive level until the initial signal edge travels to the unterminated end of the circuit and reflects back to source resistor R1.

NAC3FCA_Datasheet PDF

The total trace length in time of the simulated circuit is 2ns, which shows in the waveform as 4ns (twice the propagation time through the trace). At 2.0ns, a reduction in trace impedance is present.

The reduction in impedance correlates with the location of the ESD circuit. The length of time the impedance is low is equal to the rise-time of the input signal. HDMI specifies an edge rate of 200ps for differential trace impedance measurements.

NAC3FCA_Datasheet PDF

Figure 7 show the schematic of the simulated circuit. The transmission lines used for this simulation are ideal to remove any effect a non-ideal transmission line adds to the simulation results, allowing us to focus on effects of the ESD protection.

•Servers—typically clusters of blade servers, each blade containing one or more processors and mass storage. The video content is accessed from here, unless cached in a downstream node. A cluster has a switch fabric that connects the blades to some number of I/O modules that support high-bandwidth communication standards (10G Ethernet, etc.).

•Routers—the high-bandwidth wired portion of the network. Core routers pass information to and from other routers. Edge routers make connections between core routers and interfaces to media consumers, such as cellphone radio base stations, cable modem head ends, and DSL multiplexers.

•Radio base station—provides the stationary end of the wireless connection. It's the largest power consumer in the video delivery chain.

•Mobile multimedia device—the mobile end of the wireless connection. Important power consumers are the radio transceivers (cellphone, Wi-Fi, Bluetooth), display controller, display backlight, audio subsystem, and hard disk drive.

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In the phone example described above, the single-chip Bluetooth and the two-chip GPS chipset are connected to the application processor, while their respective software drivers are embedded into the operating system that controls the operation of the entire platform. Also, since these are independent stand-alone” systems, the Bluetooth and the GPS subsystems may operate concurrently during a network call established by the handset.

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