Attenuators and Power Splitters

If the amplitude of a signal is to be reduced for whatever reason, impedance matching forbids the use of a simple series resistor. Instead, it is necessary to use a 

If a signal has to be distributed into several loads, e.g. to trigger two TCSPC modules from the same laser, a resistive network must be used as well. A 1 2 power splitter is shown in Fig. 7.50, right. 

A wide range of attenuators is available for the commonly used SMA and BNC connector systems. Power splitters are available for splitting a signal into 2, 3 or 4 outputs. The signal amplitude at the outputs is 1/2, 1/3 and 1/4 of the input amplitude, respectively. Unused outputs of a power splitter must be terminated by 50 resistors. Attenuators and power splitters of satisfactory bandwidth can be made by soldering small 0805-size surface-mount resistors directly between the pins of SMA connectors. 

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