What Does Bandwidth of an RF Switch Module Really Mean? Hardware: Switches
Problem: All RF Switch modules have a specification known as "Bandwidth". This specification is usually in the GHz range. What does this specification mean? Solution: The bandwidth of a switch simply indicates the maximum frequency signal that the vendor believes can be routed through it with acceptable loss. For example, the PXI-2547 has a specified bandwidth of 2.7 GHz. Thus, a signal of frequency up to 2.7 GHz can be passed through the switch with acceptable loss. Any frequencies above 2.7 GHz will not be within spec. Varies by Vendor Bandwidth of a product is also thought, by many, to be its -3 dB bandwidth. This viewpoint is accurate for instruments such as digitizers where the bandwidth specification of the device is in fact the -3 dB point of the analog front end of the instrument. However, for an RF switch, the relation between bandwidth and -3 dB does not always hold true. While some vendors do in fact specify bandwidth at -3 dB, others do not. National Instruments is much more conservative on this specification. The PXI-2547 has a specified bandwidth of 2.7 GHz. However, the loss at 2.7 GHz is roughly only -1.4 dB with a -3 dB loss at 3.7 GHz. This more conservative approach ensures that higher signal integrity is preserved with National Instruments products in comparison to other vendors. For more information, refer to Understanding Key RF Switch Specifications. Related Links: Understanding Key RF Switch Specifications. Attachments:
Report Date: 05/02/2007 Last Updated: 05/02/2007 Document ID: 4919F2IH |
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