ZXFV302EV

ZXFV302EV 4:1 CHANNEL VIDEO MULTIPLEXER EVALUATION BOARD Evaluation board description The wide bandwidth of the ZXFV302 4:1 channel video Figures 1, 2 and 3 show the schematic and copper multiplexer necessitates some care in the layout of the layout of a double-sided printed circuit board suitable printed circuit. For this reason Zetex has made for evaluation of the device in the laboratory. available an Evaluation Board. BNC connector sockets allow connection to test The Evaluation Board layout serves as a useful instruments via 50 cables. The output circuit includes example for many applications, showing a practical a resistor matching circuit to present a load of 150 to implementation of the advice given below. the amplifier (equivalent to a 75 back-terminated video line) and simultaneously provide 50 output impedance. The ZXFV302EV can also be used to evaluate the ZXFV301 4:1 channel multiplexer. The ZXFV301 and ZXFV302 devices have very similar ac performance, The attenuation of this matching circuit is 15.45 dB. As with the only difference being in the active channel the multiplexer is internally configured for a voltage selection. gain of 1, the overall gain from input to output is -15.45dB. Figure 1 Circuit schematic ISSUE 1 - SEPTEMBER 2004 SEMICONDUCTORS 1ZXFV302EV PCB design A continuous ground plane is required under the A double-sided or multi-layer PCB construction is device and its signal connection paths, to provide the required, with plated-through via holes providing shortest possible ground return paths for signals and closely spaced low-inductance connections from some power supply filtering. components to the continuous ground plane (some of these holes are not visible in the figures for the Evaluation Board artworks and NC drill output can be provided if required). Figure 2 Evaluation circuit top copper layout (overall dimensions 2.5 x 2.25 inches) Figure 3 Evaluation board bottom copper layout (viewed through from top) ISSUE 1 - SEPTEMBER 2004 SEMICONDUCTORS 2