Antenna Switch Resistor Linearity for Intermodulation Distortion
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Solution Overview
Problem
Existing antenna switches in wireless communication systems, particularly those used in W-CDMA systems, suffer from significant intermodulation distortion due to uneven RF signal supply to gate resistors, leading to reduced reception sensitivity and increased chip area and cost when attempting to mitigate this issue.
Innovation Solution
The implementation of a semiconductor device with high-linearity resistors as coupling resistors in the antenna switch, specifically using a combination of channel and n+ resistors to reduce intermodulation distortion while minimizing chip area and cost, by configuring the resistors to have higher current-voltage linearity than traditional resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional semiconductor resistors are used as gate-control resistors in antenna switches, then the device structure is simple and manufacturing is easy, but intermodulation distortion increases due to nonlinear current-voltage characteristics
Solution Approach 1:
The patent changes the electrical parameters of the resistor by using a composite structure of channel resistor and n+ resistor, transforming the nonlinear semiconductor resistor into a structure with more linear current-voltage characteristics, thereby reducing intermodulation distortion while maintaining manufacturing compatibility
Solution Approach 2:
The patent employs a composite resistor structure combining channel resistor and n+ resistor layers, utilizing different semiconductor regions with complementary characteristics to achieve improved linearity and reduced intermodulation distortion
2Object-generated harmful factors
If the resistance value of gate-control resistors is increased to reduce intermodulation distortion, then intermodulation distortion decreases, but chip area increases
Solution Approach 1:
The patent changes the resistance configuration strategy from using a single high-value resistor to a composite structure that achieves the required linearity with optimized area, balancing performance and size constraints
Solution Approach 2:
The patent divides the gate-control resistor into multiple segments (channel resistor and n+ resistor), allowing each segment to contribute differently to the overall function, achieving linearity improvement without proportional area increase
3Object-generated harmful factors
If new high-linearity devices are developed to reduce intermodulation distortion, then intermodulation distortion decreases, but development time and cost increase significantly
Solution Approach 1:
The patent modifies parameters of existing conventional components (resistor structure and material composition) rather than developing entirely new devices, achieving performance improvement through parameter optimization within the existing technology framework
Solution Approach 2:
The patent uses existing semiconductor structures (channel and n+ layers) that are already part of the HEMT fabrication process, copying and reconfiguring existing elements rather than introducing completely new device types
4Object-generated harmful factors
If all resistors in the gate-control circuit are replaced with high-linearity resistors, then intermodulation distortion decreases, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies the high-linearity composite resistor structure specifically to the gate-control resistor where it is most needed for reducing intermodulation distortion, rather than uniformly replacing all resistors, optimizing the balance between performance and complexity
Solution Approach 2:
The composite resistor structure serves multiple functions: it provides the required resistance value, achieves improved linearity, and maintains compatibility with existing semiconductor fabrication processes, reducing overall system complexity
Data Source
AI summary
Reduction of intermodulation distortion in a high-frequency switch is achieved. A semiconductor device (1) includes an antenna terminal (ANT_LB), plural external terminals (RX_LB, TX_LB, TRX_LB, TERM_LB), plural first high-frequency switches (101 to 104), and plural control terminals. Each first high-frequency switch includes plural first field-effect transistors, plural first resistors (Rg_1 to Rg_6) connected to the gate terminals of the first field-effect transistors, and a second resistor (Rc) disposed between the corresponding control terminal and the first resistors. The second resistor in the first high-frequency switch disposed between the first terminal supplied with an RF transmission signal and an RF reception signal of a frequency division duplex system and the antenna terminal is configured so that linearity of current-voltage characteristics thereof is higher than linearity of current-voltage characteristics of the first resistor.