Switching Device Phase Selection Reduces Intermodulation Distortion
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Solution Overview
Problem
Conventional high-frequency switching devices in mobile communication devices face challenges in reducing intermodulation distortion (IMD) without increasing semiconductor die area or signal loss, and existing methods to mitigate IMD either increase cost or require complex technology.
Innovation Solution
The implementation of a switching device with selectable phase shifting modes, utilizing phase shifter circuits composed of series-coupled FETs and LC filters to optimize phase shift and attenuate out-of-band blocker signals, thereby reducing IMD3.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the number of FETs in each switching arm is increased to reduce intermodulation distortion, then intermodulation distortion is reduced, but semiconductor die area and signal loss increase
Solution Approach 1:
The patent implements selectable phase shifting modes that dynamically adjust the phase relationship between switching arms. By changing the phase shift amount (0°, 45°, 90°, 135°, 180°, 225°, 270°, or 315°), the system optimizes IMD cancellation without requiring additional FETs, thus reducing die area while maintaining low distortion performance.
Solution Approach 2:
The system changes the phase shift parameter to optimize performance. By selecting different phase shifting modes, the patent adjusts the phase relationship between differential switching arms to achieve optimal IMD cancellation, avoiding the need to increase the number of FETs and thereby reducing die area consumption.
2Object-generated harmful factors
If the number of FETs in each switching arm is increased to reduce intermodulation distortion, then intermodulation distortion is reduced, but signal loss increases
Solution Approach 1:
The patent uses dynamic phase shifting to cancel IMD products. By adjusting the phase shift between switching arms, the system achieves IMD reduction through destructive interference of distortion products rather than through increased FET count, thereby avoiding additional signal loss that would result from more series FETs.
Solution Approach 2:
The patent converts the harmful IMD products generated by switching arms into beneficial cancellations. By introducing phase-shifted versions of the same signal through different switching arms, the IMD products destructively interfere with each other, turning the harmful distortion into a benefit without requiring additional FETs that would cause signal loss.
3Object-generated harmful factors
If a charge pump is used to increase the high voltage for enabling switching arms to reduce IMD distortion, then intermodulation distortion is reduced, but device cost increases
Solution Approach 1:
The patent uses dynamic phase shifting control to reduce IMD without requiring voltage boosting circuitry. By controlling the phase relationship between switching arms, the system achieves IMD cancellation through signal processing rather than through increased voltage, eliminating the need for expensive charge pump circuits.
Solution Approach 2:
The patent replaces the mechanical/electrical charge pump system with a phase-shifting control system. Instead of using a charge pump to increase voltage for IMD reduction, the patent uses phase-shifting networks and control logic to achieve the same goal, simplifying the device and reducing cost.
Data Source
AI summary
According to one exemplary embodiment, a switching device with phase selection terminals to select between at least two phase shifting modes to reduce intermodulation distortion in the switching device includes a first phase selection terminal to select a first phase shifting mode of the switching device by enabling a first phase shifter in a first phase shifting switching branch coupled to an input of the switching device. The switching device further includes a second phase selection terminal to select a second phase shifting mode of the switching device by enabling a second phase shifting switching branch coupled to the switching device input. The intermodulation distortion in the switching device is reduced by selecting one of the first and second phase shifting modes. The switching device may further include a number of FETs coupled in series between an output of the switching device and the first and second phase shifting switching branches.