Power Divider Circuit Impedance Matching
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Solution Overview
Problem
The Wilson power divider's narrow line width on thin substrates with high dielectric constants is sensitive to manufacturing precision, affecting its performance in power distribution and isolation at different frequencies.
Innovation Solution
A power divider design with 50 ohm microstrip lines of 0.2 mm width and a closed rectangular structure, including an impedance converter and isolation element, ensures better matching and isolation performance across various frequencies, reducing manufacturing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a thin substrate with high dielectric constant is used, then the line width can be reduced, but the manufacturing precision requirement increases significantly
Solution Approach 1:
The patent changes the characteristic impedance parameter from 50 ohms to 70.7 ohms for the transmission lines. This parameter change allows the use of thinner substrates with high dielectric constants while maintaining acceptable manufacturing tolerances, as the 70.7 ohm impedance is specifically optimized for 3-dB power division and reduces sensitivity to line width variations
Solution Approach 2:
The patent pre-calculates and sets the transmission line length to exactly one-quarter of the wavelength at the design frequency. This preliminary dimensioning ensures that the power divider achieves the desired 3-dB power distribution and isolation characteristics while being less sensitive to manufacturing variations in line width
2Length of stationary object
If the line width is reduced for thin substrates, then the substrate thickness can be reduced, but the power distribution performance becomes more sensitive to manufacturing variations
Solution Approach 1:
The patent modifies the transmission line impedance parameter to 70.7 ohms, which is specifically chosen to achieve 3-dB power division. This parameter change makes the power distribution performance less sensitive to manufacturing variations in line width and substrate thickness, thereby improving reliability while allowing for thinner substrates
Solution Approach 2:
The patent employs a symmetric Wilson power divider topology where both transmission lines have identical characteristics (70.7 ohm impedance, quarter-wavelength length). This symmetry ensures balanced power distribution and reduces sensitivity to manufacturing variations, as any deviations affect both lines equally and tend to cancel out
3Area of stationary object
If the line width is reduced, then the device size can be reduced, but the isolation between output ports deteriorates
Solution Approach 1:
The patent sets the transmission line impedance to 70.7 ohms and length to quarter-wavelength, which creates specific electrical characteristics that improve isolation between output ports. The quarter-wavelength transformation at the design frequency provides natural isolation, reducing the need for large physical dimensions while maintaining isolation performance
Solution Approach 2:
The patent introduces a 70.7 ohm isolation resistor connected between the two output ports. This intermediary element provides a dedicated path for isolating the output ports, ensuring that signals from one output do not couple to the other, thereby maintaining isolation performance even with reduced line widths and device size
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves improved matching performance and isolation of at least 18 dB return loss and 24 dB isolation between output ports, maintaining effectiveness on thin substrates with high dielectric constants across frequency bands like 5.5 GHz and 2.45 GHz, with larger manufacturing tolerances.
Implementation Method 1
two 70.7 ohm quarter-wave transmission lines
Implementation Method 2
impedance converter
Data Source
AI summary
A small scale power divider which is less susceptible to large tolerances in the manufacture includes a substrate and a power dividing circuit thereon. The power dividing circuit includes an input port, a first output port, a second output port, an impedance converter, a first microstrip line, and a second microstrip line. An end of the first microstrip line is connected to the impedance converter, another end of the first microstrip line is connected to the first output port. An end of the second microstrip line is connected to the impedance converter, another end of the second microstrip line is connected the second output port.