RF power splitter design as per 2-way Wilkinson circuit
A Wilkinson power splitter is a type of RF (Radio Frequency) passive component that is commonly used to divide power among multiple ports in a circuit. The design of a Wilkinson power splitter is based on the Wilkinson divider topology, which provides equal power division between output ports while maintaining good impedance matching. The design can also be used as 2-way RF power combiner.
Wilkinson power splitters are widely used in RF and microwave systems, including applications in communication systems, test and measurement equipment, and radar systems. They are particularly useful in scenarios where equal power distribution is essential, and minimal signal reflections are required.
Let us explore 2-way wilkinson RF power splitter design at 800MHz using dielectric substrate having εr of 4.6. The same design can be extended for N-Way power divider or splitter such as 8-WAY and 16-WAY.
As shown, the basic Wilkinson power splitter consists of a three-port network with a resistor at each port and two transmission lines. Wilkinson power divider is the robust among all designs. It will have all the output ports matched. It will have only reflected power which will be dissipated. It provides better isolation between output ports in comparison to T-junction power divider. Figure above mentions both geometry layout as well as transmission line equivalent circuit of the power splitter.
Power splitter circuit simulation
The figure depicts wilkinson 2-way power splitter circuit used for simulation using Microwave Office software. Simulate the rf circuit from frequency 500 to 1100 MHz and check the results as shown. Set the microstrip substrate parameters as shown in the table below in the simulation circuit.
|Relative Dielectric Constant(εr)
|Rho(Metal Bulk resistivity normalized to gold)
|Tand(Loss tangent of dielectric)
Result 1 : Return loss at ports
Result 2: Splitter power loss chart
The figure depicts results of our design. As mentioned S11, S22, S33 are better than -15dB. S21 and S31 are better than about -3dB.
RF power divider Layout
The figure depicts final layout of 2way rf power splitter as per wilkinson design concepts mentioned. After the basic layout is generated, the same is modified as per PCB requirement and placement of RF connectors. The mounting of chip resistors of value 50 Ohm and 100 Ohm is also made manually. Refer microstrip line basics and types which will help rf designer to understand concepts before RF circuit design as mentioned in this example.
In summary, during 2-way Wilkinson power splitter design, engineers often use RF simulation tools (Microwave office or ADS) and follow best practices to optimize the performance of the power splitter circuit. Proper impedance matching, attention to component values and adherence to the design principles contribute to the success of the Wilkinson power splitter in various RF applications.
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