The Wilkinson power divider was first introduced by Ernest Wilkinson, who proposed that the power divider configuration could split an input signal into two in-phase output signals.
The performance of a Wilkinson power divider can be improved by adding an 𝛌/4 transformer in front of the power division step.
The advantages of Wilkinson power dividers are their simple structure, compact size, high suppression factor, high isolation between output ports, wide stopband, and broad bandwidth characteristics.
Wilkinson power dividers are significant components in modern wireless communication systems
In modern wireless communication systems, power dividers are significant components used in power amplifiers, mixers, active circulators, and phase shifters. Among power dividers, Wilkinson power dividers are widely used due to their simple construction, narrow bandwidth, and reliable performance.
Wilkinson power dividers are the basic building blocks in communication circuits and are most commonly seen in ultra-wideband (UWB) circuits, antenna array systems, and RF front modules. As Wilkinson power divider applications expand, engineers continue to work to miniaturize this conventional divider to save on costs and space.
In this article, we will discuss modified, compact-size Wilkinson power dividers and how they can be applied in the field.
An Overview of Wilkinson Power Dividers
The Wilkinson power divider was first introduced by Ernest Wilkinson, who proposed that the power divider configuration could split an input signal into two in-phase output signals. It was discovered that the Wilkinson power divider can also be used as a power combiner, where the structure takes two input signals of equal phases for combining. The Wilkinson power divider offers outputs with equal phase as well as with a broad bandwidth of about 1 octave.
The Wilkinson power divider is a three-port power divider—otherwise known as a two-way power splitter. The output ports are usually terminated by a series resistor, which provides the isolation between output ports. This isolation is obtained by terminating the output ports by a series resistor. The value of the series resistor should be equal to 2Zo, where Zo is the system impedance. The lines are equal to a quarter wavelength and the characteristic impedance is equal to √2Zo .
The performance of a Wilkinson power divider can be improved by adding a 𝛌/4 transformer in front of the power division step. The bandwidth can be increased from octave to decade by using multi sections. By varying the values of the series resistor and the 𝛌/4 sections, one Wilkinson power divider application can be to mitigate unequal power division.
Advantages of Wilkinson Power Dividers
The advantages of conventional Wilkinson power dividers include:
High suppression factor
High isolation between output ports
Broad bandwidth characteristics
Modified Microstrip Wilkinson Power Divider Applications in GSM Communication Systems
In GSM communication circuits, modified microstrip Wilkinson power dividers are commonly applied, as compact size and harmonic suppression can bring added value to these power dividers.
Modified microstrip Wilkinson power dividers are created by modifying a conventional Wilkinson power divider. By modifying the Wilkinson power divider with one open stub, one radial resonator, and two rectangular resonators, the harmonics of order two to six can be suppressed. The open stub, radial, and rectangular resonators form the low pass filters in the modified structure. Two low pass filters of this kind are introduced into the quarter wavelength branch lines to suppress the higher-order harmonics.
This modified Wilkinson power divider suppresses unwanted harmonics due to the presence of two rectangular resonators and the open stubs. The open stub and the rectangular resonators act as suppressor cells. The rectangular resonator is responsible for the wide stopband of the modified power divider.
Advantages to Modified Microstrip Wilkinson Power Dividers
The advantages of a modified microstrip Wilkinson power divider are similar to that of a conventional Wilkinson power divider, including:
Harmonic suppression with high attenuation level
Excellent insertion loss in the passband
Miniaturized Low-Loss Wilkinson Power Dividers Used in the RF Front Module
In a miniaturized low-loss Wilkinson power divider used in the RF front module, size reduction is achieved by folding the quarter-wave branch lines into tightly coupled meander lines. The quarter wavelength transmission lines are folded into four meander lines, where the aspect ratio is not fixed. The aspect ratio can be adjusted by altering the number of folds. The width of the transmission lines determines the insertion loss and the manufacturability of the modified Wilkinson structure. The sharp microstrip corners are replaced by smooth, curvy bends to avoid ill effects at high frequencies. To ensure isolation, a chip resistor of 100 ohms is included between the output ports. This miniaturized low-loss Wilkinson power divider is used in antenna array feed networks, amplifiers, and mixers.
Modified Wilkinson power divider applications are substantial and modern wireless communication systems make great use of these types of power dividers. When working with these power dividers, it is important to use the best set of design and analysis tools you can find. Cadence’s full-wave electromagnetic simulation software can support structural modifications in conventional Wilkison power dividers so you can achieve a modified structure.