Self-Matching Phase Shifter Circuit for Low Return Loss
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Solution Overview
Problem
Variable phase shifters that rely on reactive devices for phase shift induction face impedance mismatch issues, leading to reflections and power loss as the number of phase shifter elements increases, disrupting the impedance match and increasing return loss.
Innovation Solution
A self-matching variable phase shifter/attenuator design using incremental impedance matched elements with shunt and series reactive components, where the number of closed ground switches is alternated with open bypass switches to maintain impedance matching across a range of phase shifts, allowing for fine discrete steps while keeping input and output impedance constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If incremental phase shifter elements using reactive devices are added to achieve fine phase shift steps, then phase shift precision is improved, but impedance mismatch increases causing reflections and power loss
Solution Approach 1:
The phase shifter is divided into multiple incremental elements, each contributing a small phase shift step. By segmenting the total phase shift into many small increments, each element introduces minimal reactive impedance, preventing significant impedance mismatch while achieving fine phase resolution when elements are combined
Solution Approach 2:
Resistive components are introduced as intermediary elements between the reactive phase-shifting components and the signal path. These resistive elements act as impedance buffers that match the reactive impedance to the real impedance system, reducing reflections and power loss while allowing the reactive components to provide the desired phase shift
2Adaptability or versatility
If the number of phase shifter elements is increased to achieve broader phase shift range, then phase shift range is improved, but return loss increases disrupting impedance match
Solution Approach 1:
The phase shifter is divided into multiple incremental elements, each contributing a small phase shift step. By segmenting the total phase shift into many small increments, each element introduces minimal reactive impedance, preventing significant impedance mismatch while achieving fine phase resolution when elements are combined
Solution Approach 2:
The invention changes the impedance parameters by introducing resistive elements that transform the reactive impedance of the phase-shifting components into a matched real impedance. This parameter transformation maintains impedance match across different phase shift states, enabling broad phase shift range without degrading return loss
3Object-affected harmful factors
If reactive impedance is increased to achieve desired phase shift magnitude, then phase shift magnitude is improved, but impedance matching deteriorates causing reflections
Solution Approach 1:
Resistive components are introduced as intermediary elements between the reactive phase-shifting components and the signal path. These resistive elements act as impedance buffers that match the reactive impedance to the real impedance system, reducing reflections and power loss while allowing the reactive components to provide the desired phase shift
Solution Approach 2:
The invention converts the harmful reactive impedance that causes reflections into a beneficial matched impedance system. By transforming the reactive impedance through resistive elements, the previously harmful impedance mismatch becomes a matched condition that allows maximum power transfer while maintaining the desired phase shift function
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 solution enables variable phase shifting with minimal return loss, maintaining a consistent impedance match and reducing reflections, allowing for precise phase control while preventing power loss across a broad range of phase shifts.
Implementation Method 1
an impedance device 301, such as a capacitor (as shown in FIG. 3a) or an inductor (not shown for the sake of simplicity) having an reactance Z1
Implementation Method 2
an impedance device 301, such as a capacitor (as shown in FIG. 3a) or an inductor (not shown for the sake of simplicity) having an reactance Z1
Data Source
AI summary
A self-matching phase shifter/attenuator including several incremental impedance matched phase shifter/attenuator elements is disclosed. Each incremental impedance matched phase shifter element comprises a reactive component (such as either a capacitor or inductor) that can be coupled in shunt to the signal path. The shunt reactive component is coupled in series with a ground switch. When closed, the ground switch connects the shunt reactive component to ground. When the ground switch is open, the switch removes the shunt reactive component from the circuit. In addition, each incremental impedance matched phase shifter element comprises a series reactive component having a reactance that is typically equal and inverse of that of the shunt reactive component.