Switched Comb-Finger Capacitor Array for PVT-Stable Phase Shifting
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Solution Overview
Problem
Conventional variable capacitors used in reflection-type phase shifters are sensitive to changes in process, voltage, and temperature (PVT), leading to poor PVT consistency and reduced phase shifting accuracy and resolution.
Innovation Solution
A variable capacitor design featuring a comb structure with electrically conductive fingers and switches, allowing for precise control of capacitance values through an array structure, providing stability against PVT changes and enabling small capacitance steps and large variable capacitance ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a varactor is used to implement a variable reflective load, then the capacitance can be changed to adjust impedance, but the capacitance value becomes sensitive to PVT changes, deteriorating phase shifting accuracy and resolution
Solution Approach 1:
The variable capacitor is segmented into multiple fixed capacitance units arranged in an array, where each unit can be independently switched. This segmentation replaces the continuous but PVT-sensitive varactor capacitance with discrete, stable capacitance values, eliminating sensitivity to process, voltage, and temperature variations while maintaining capacitance adjustability through switch control.
Solution Approach 2:
The invention introduces switches to dynamically reconfigure the connection of capacitance units in the array, enabling the capacitance value to be changed from a static structure. This dynamic switching mechanism provides adaptability equivalent to a varactor while using stable, PVT-insensitive fixed capacitance units, thus resolving the contradiction between adaptability and reliability.
2Ease of operation
If a varactor is used to change capacitance for impedance adjustment, then phase shifting is achieved, but the phase shifting accuracy and resolution are severely deteriorated due to poor PVT consistency
Solution Approach 1:
By segmenting the variable capacitor into multiple fixed capacitance units with precise, stable values, the invention enables precise control over the total capacitance. This segmentation allows for fine-grained adjustment of impedance and phase shift with high accuracy, overcoming the precision limitations of PVT-sensitive varactors while maintaining operational ease through switch control.
Solution Approach 2:
The invention changes the parameter approach from using a continuously variable but PVT-sensitive capacitance (varactor) to using discrete, stable capacitance values that can be selectively combined. This parameter change strategy achieves phase shifting capability while significantly improving phase shifting accuracy by eliminating PVT-induced parameter drift.
3Manufacturing precision
If switches are used to control the quantity of capacitors in a capacitor array, then precise capacitance control is achieved with small capacitance steps, but the device complexity increases
Solution Approach 1:
The capacitor array is segmented into multiple fixed capacitance units, each controllable by an individual switch. This segmentation enables precise capacitance control by selectively activating specific units, achieving fine capacitance steps. The modular segmented structure makes the complexity manageable through systematic design and potential integration techniques.
Solution Approach 2:
Dynamic switch control enables precise capacitance selection from the array of fixed units. The switching mechanism provides the necessary complexity to achieve precise capacitance control, but this complexity is justified by the significant improvement in manufacturing precision and PVT stability compared to varactor-based solutions.
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 achieves strong stability against PVT changes, improving phase shifting accuracy and resolution by allowing for precise capacitance control, thereby enhancing the performance of reflection-type phase shifters.
Implementation Method 1
a first comb structure 23 and a first set of fingers 25, where the first comb structure includes a plurality of comb teeth, the first set of fingers includes at least one finger, the finger in the first set of fingers is disposed between at least two comb teeth of the first comb structure
Implementation Method 2
A dielectric is sandwiched between the finger in the first set of fingers and the comb tooth of the first comb structure, and a dielectric is sandwiched between the finger in the second set of fingers and the comb tooth of the second comb structure
Data Source
AI summary
This application discloses a variable capacitor, a reflection-type phase shifter, and a semiconductor device, which relate to the technical field of electronics, so as to resolve the problem that a capacitance value of a variable capacitor is sensitive to changes in PVT. The variable capacitor includes: a first comb structure and a first set of fingers, where the first comb structure includes a plurality of comb teeth, the first set of fingers includes at least one finger, and the finger in the first set of fingers is disposed between at least two comb teeth of the first comb structure, without electrical contact; a second comb structure and a second set of fingers, where the second comb structure includes a plurality of comb teeth.