RF Power Divider & Power Splitter Differences & Applications
There are many circumstances in RF applications where there is a need to redirect a signal into two or more separate ports simultaneously. There are a few different components capable of this, but two of the most common are RF power dividers/combiners and power splitters. Power dividers/splitters are often considered the same category of components, though some consider there to be a divide in the construction and use case of these components.
One definition of a power divider is a component with 3 or more ports where each port presents an equivalent characteristic impedance at each port and the “output” ports exhibit a uniform division of energy from the “input” port. In this case, a power divider provides a good impedance match amongst all of the ports, including a source match. Hence, a power divider can be used for highly accurate comparison measurements . For instance, it may be needed to split a signal between two or more different measurement apparatus, such as frequency, power, phase, distortion, or other signal characteristics. Power dividers defined in this way are also intrinsically bi-directional and can also be used as power combiners. The equivalent circuit for this device is a multi-resistor network where each port of the power divider/combiner network has a necessary resistance to have an equivalent port impedance that matches with the characteristic impedance of the transmission line impedance.
A power splitter, on the other hand, can be defined in the simplest terms as a two-resistor network (this could be an equivalent circuit). In this design the “input” port of the equivalent circuit is without a resistor and the “output” ports have a two-resistor configuration that results in an input impedance that matches the characteristic impedance of the transmission lines. This minimizes uncertainty in source leveling or ratio measurements with good output match to RF sources.
Power Splitters are often used for gain compression, power, and gain testing. A source signal is sent to a power splitter that drives both a DUT followed by a detector and a detector without the DUT. Analyzing the signals from the split signals provides an accurate comparison of the signals and removes the re-reflected signals allowing for repeated gain measurements at different RF power levels without recalibration.
Power dividers can be used for any occasion where a signal needs to be evenly split or combined into any number of ports, such as an 8-way RF power divider. This includes intermodulation distortion (IMD), diversity gain, multi-element antenna arrays etc.
