Differences between current version and predecessor to the previous major change of ImpedanceMatching.
Other diffs: Previous Revision, Previous Author, or view the Annotated Edit History
| Newer page: | version 5 | Last edited on Monday, August 11, 2003 7:29:05 pm | by CraigBox | |
| Older page: | version 3 | Last edited on Monday, August 11, 2003 4:31:32 pm | by PerryLorier | Revert |
@@ -1,8 +1,8 @@
-Any driver on a circuit that has a non-zero output [Impedance]
requires ImpedanceMatching to deliver the maximum amount of power to the load.
+Any driver on a circuit that has a non-zero OutputImpedance
requires ImpedanceMatching to deliver the maximum amount of power to the load.
-If the load InputImpedance (resistance)
is equal to the drivers OutputImpedance, the power at the load is at a maximum. If there is a TransmissionLine connecting the driver to the load, it must also have a CharacteristicImpedance close to the OutputImpedance, so as to instantaneously load the driver to the right load, to prevent ringing in the circuit. Imagine you take a TransmissionLine and make an incision, both sides of the TransmissionLine will be the same CharacteristicImpedance as the original line. This can be modeled as a amplifier with unity gain (0dB) and an InputImpedance and
OutputImpedance equal to the CharacteristicImpedance of each respective side, ensuring maximum power is transferred.
+If the load InputImpedance (which can be modelled as a [Resistance] at a single frequency
is equal to the drivers OutputImpedance, the power at the load is at a maximum. If there is a TransmissionLine connecting the driver to the load, it must also have a CharacteristicImpedance close to the OutputImpedance, so as to instantaneously load the driver to the right load, to prevent ringing in the circuit. Imagine you take a TransmissionLine and make an incision, both sides of the TransmissionLine will be the same CharacteristicImpedance as the original line. This can be modeled as a amplifier with unity gain (0dB) and an InputImpedance /
OutputImpedance equal to the CharacteristicImpedance of each respective side, ensuring maximum power is transferred.
+The reason why [SCSI] busses need to be terminated is that all the drive inputs have a high InputImpedance which means they don't draw power over the bus (which is a TransmissionLine). The terminators at the end of a [SCSI] Chain ensure that there is enough load on the drivers to maintain proper signal levels. The result is also that when the rising edge of the signal gets to the end of the cable, it has an (ImpedanceMatched) path to ground, thus signals do not reflect back down the line, degrading signal integrity and lowering the maximum speed we can drive the bus.
-Hey. This is getting fairly far from the topic of 'linux'; could you please at least remove all the wikiwords and define these terms on the same page?
- zcat(1)
-
-[IMHO], It's kinda on topic as it interests people that are trying to maintain Unix machines, mostly in understanding why you need Bus Termination ([SCSI] anyone? [ThinNet]?), and other related things (Why are there 3.3v [PCI] cards?). Lets see what JamesSpooner adds, and perhaps look at condensing it/removing irrelevant material in a few months if it's not used.
-- PerryLorier
+-----
+CategoryElectronics
