Transformer Phase Shifter for Multi-Band Impedance Matching
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Solution Overview
Problem
Existing phase shifters in high-frequency circuits fail to provide the necessary phase-shift operations for multiple frequency bands, particularly in communication terminal apparatuses, where impedance matching requires specific phase shifts for low and high bands, and current filter-type phase shifters suffer from increased insertion loss and altered cutoff frequencies.
Innovation Solution
A phase shifter design incorporating a transformer with magnetically coupled coils and a parasitic inductance component, along with an impedance adjustment circuit featuring a reactance element and inter-coil capacitance, allows for adjustable phase-shift amounts across frequency bands, using a coupling coefficient and additional capacitors to achieve desired phase shifts while maintaining a compact structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-pass-filter-type phase shifter is used to shift the phase of a high-band signal, then the phase-shift amount in the high band is improved, but the phase-shift amount in the low band becomes excessive and insertion loss increases
Solution Approach 1:
The phase shifter is divided into multiple independent phase-shifting circuits, each dedicated to a specific frequency band. The first phase-shifting circuit handles the low band while the second phase-shifting circuit handles the high band, allowing each segment to be optimized for its designated band without adversely affecting other bands.
Solution Approach 2:
Each phase-shifting circuit is designed with specific circuit constants optimized for its target frequency band. The low-band circuit has constants optimized for low-band phase shifting, while the high-band circuit has constants optimized for high-band phase shifting, ensuring that each local segment performs its specific function with high quality.
2Measurement precision
If a low-pass-filter-type phase shifter is used to shift the phase of a low-band signal, then the phase-shift amount in the low band is improved, but the phase-shift amount in the high band becomes excessive and cutoff frequency decreases
Solution Approach 1:
The phase shifter is divided into multiple independent phase-shifting circuits, each dedicated to a specific frequency band. The first phase-shifting circuit handles the low band while the second phase-shifting circuit handles the high band, allowing each segment to be optimized for its designated band without adversely affecting other bands.
Solution Approach 2:
Each phase-shifting circuit is designed with specific circuit constants optimized for its target frequency band. The low-band circuit has constants optimized for low-band phase shifting, while the high-band circuit has constants optimized for high-band phase shifting, ensuring that each local segment performs its specific function with high quality.
3Device complexity
If a single phase-shifting circuit is used for both low band and high band impedance matching, then the device complexity is reduced, but the ability to perform independent phase-shift operations for each frequency band is lost
Solution Approach 1:
The phase shifter is divided into multiple independent phase-shifting circuits, each dedicated to a specific frequency band. The first phase-shifting circuit handles the low band while the second phase-shifting circuit handles the high band, allowing each segment to be optimized for its designated band without adversely affecting other bands.
Solution Approach 2:
The phase shifter maintains a unified structure that can handle multiple frequency bands through the coordinated operation of multiple phase-shifting circuits. Each circuit is specialized for its band, but together they provide universal impedance matching capability across both low and high bands.
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
Enables precise phase shifting in accordance with frequency bands, facilitating impedance matching across a wide range, reducing insertion loss, and maintaining a compact, simple structure, thereby improving communication terminal apparatus performance.
Implementation Method 1
a transformer connected between a first port and a second port and including a first coil, a second coil that is magnetically coupled to the first coil
Data Source
AI summary
A phase shifter includes a transformer including a first coil, a second coil that is magnetically coupled to the first coil, and a parasitic inductance component, and an impedance adjustment circuit including a reactance element connected to the transformer. The impedance adjustment circuit includes an input/output capacitor connected between a first port and a second port of the transformer, and the input/output capacitor is defined by an inter-coil capacitance generated between the first coil and the second coil and an input/output additional capacitor connected between the first port and the second port.