Varactor Phase Shifter Linearizing C-V Curve
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Solution Overview
Problem
The non-linear capacitance-voltage (C-V) curve of varactors in phase shifters leads to non-linear phase-tuning curves, requiring high-resolution digital-to-analog converters and increasing digital compensation noise, complicating the implementation of phase shifters in wireless communication applications.
Innovation Solution
The phase shifter and load device employ varactor units connected in parallel or distributed across inductive components with different reference and control voltages, effectively linearizing the C-V curve to achieve a more linear phase-tuning response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional varactor is used in the phase shifter, then the phase shifter can provide phase tuning functionality, but the phase-tuning curve becomes non-linear due to the varactor's non-linear C-V curve
Solution Approach 1:
The single varactor is divided into multiple parallel-connected varactor units, each with different capacitance values. This segmentation allows the overall capacitance to be adjusted in a more linear fashion across different control voltages, improving the phase-tuning linearity while maintaining phase tuning functionality
Solution Approach 2:
Different varactor units are assigned different capacitance values to compensate for the non-linear C-V characteristics at different operating points. This local differentiation in capacitance values ensures that the aggregate phase response remains linear across the full tuning range
2Productivity
If the control voltage is set within a specific range where the C-V curve slope is sharp, then the capacitance value changes rapidly, but the DAC conversion noise increases severely
Solution Approach 1:
By dividing the capacitance adjustment into multiple discrete varactor units with different capacitance values, the system can select combinations that avoid regions of excessively high dC/dV, thereby reducing DAC conversion noise while maintaining tuning speed
Solution Approach 2:
The varactor units are pre-configured with specific capacitance values during design to preemptively avoid the sharp slope regions of the C-V curve during operation, thus preventing excessive DAC conversion noise before it occurs
3Manufacturing precision
If digital compensation scheme is applied to linearize the phase-tuning curve, then the phase-tuning linearity improves, but the digital-block area increases due to the need for high-resolution DAC
Solution Approach 1:
The capacitance control is segmented into multiple varactor units with different capacitance values, which can be independently controlled with lower-resolution DACs. This approach achieves linear phase tuning without requiring a single high-resolution DAC, thereby reducing the digital-block area
Solution Approach 2:
Instead of using a single high-resolution DAC to precisely control one varactor, the system uses multiple lower-resolution DACs to control multiple varactor units. This partial control approach achieves the same or better linearity with reduced digital complexity and smaller digital-block area
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
This approach simplifies the digital compensation scheme, reduces digital-block area requirements, and minimizes DAC conversion noise by linearizing the phase-tuning curve, enhancing the efficiency of phase shifters in wireless communication systems.
Implementation Method 1
at least one of the load devices includes a plurality of first varactor units each having a first node and a second node
Data Source
AI summary
A phase shifter and related load device are provided. The phase shifter includes a phase shifter core and load devices. The phase shifter core has an input port for receiving an input signal, an output port for outputting an output signal, and connection ports. The load devices are coupled to the connection ports, respectively. At least one of the load devices includes first varactor units each having a first node and a second node, where first nodes of the first varactor units are coupled to a first voltage, second nodes of the first varactor units are respectively coupled to a plurality of second voltages, and the second voltages include at least two voltages different from each other. The phase shifter and related load device are capable of mitigating effects resulted from varactor's non-linear C-V curve.