3 What is More Important for High-Speed Interface and Video Systems

System designers often need to make trade-offs between specifications in order to achieve optimal performance for the target application. The trade-off between RON and BW is important for high-speed interface and video signals. No matter how low Ron can be maintained in the chip manufacturing process, they still form an undesired low-pass filter that attenuates the mux output signal. Meanwhile, low RON muxes have larger parasitic capacitance that reduce bandwidth and cause signal distortion. Also, low-RON muxes require large chip sizes, which increases the mux cost.

There are several key features to consider when selecting the mux to use in a particular application. High-speed applications have unique requirements (with respect to the minimum acceptable 3 dB bandwidth). Understanding the bandwidth capability of a signal mux is key for high-speed interface and video systems

So what should be the min BW for a given datarate. A good rule of thumb is BW should be greater than or equal to 1.5 or 2 times Niquist.  For example, USB2 (240 MHz) times 1.5 is 360 MHz – 480 MHz.  Obvious, high bandwidth will provide sharper edges, but  you don't want too much BW.  Too much BW can have the undesired affect of passing unwanted signal (noise).