RF Switching Circuit Control for Large-Swing Signal Linearity
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Solution Overview
Problem
Conventional switching devices in wireless communication systems face challenges in handling large swing signals without disrupting transmitter operations, requiring characteristics like low insertion loss, low distortion, and high input range, which are difficult to achieve due to circuit complexity.
Innovation Solution
A switching device comprising a first switching circuit and a control circuit, utilizing a field-effect transistor and resistive circuits to selectively couple signals to amplifying circuits, with control nodes and resistive circuits arranged to manage voltage levels and current flow, ensuring low distortion and high linearity during both receiving and transmitting modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the switch is installed in series with the receiver to enable switching between receiver and transmitter, then the receiver can be coupled to the antenna, but the switch cannot handle large swing signals without disrupting transmitter operation
Solution Approach 1:
The patent introduces a control circuit as an intermediary between the large swing signal and the switching circuit. This control circuit includes a first control circuit that generates a control signal based on the large swing signal, and a second control circuit that processes this control signal to drive the switching circuit. This intermediary structure prevents the large swing signal from directly affecting the switching circuit, thereby resolving the contradiction between switching capability and transmitter operation stability.
2Device complexity
If the switching circuit is directly controlled by the large swing signal, then the switching operation can be simplified, but the distortion increases and linearity deteriorates
Solution Approach 1:
The patent divides the control circuit into multiple segments: a first control circuit that generates the control signal, a second control circuit that processes the control signal, and a switching circuit that performs the actual switching. This segmentation allows each part to be optimized for its specific function, maintaining signal linearity while managing overall complexity.
3Adaptability or versatility
If the switch is designed to handle large swing signals, then the input range can be increased, but the insertion loss and distortion characteristics deteriorate
Solution Approach 1:
The control circuit acts as an intermediary that converts large swing signals into appropriate control signals for the switching circuit. This allows the switching circuit to operate within its optimal range while still handling large input signals, thereby maintaining low insertion loss and distortion characteristics while increasing the effective input range.
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 the switching device to effectively handle large swing signals with low distortion and high linearity, maintaining optimal performance in both receiving and transmitting modes without reducing RF signal input or output power.
Implementation Method 1
The switching circuit comprises a field-effected transistor and a first resistive circuit. The field-effected transistor has a gate node coupled to the first control signal
Implementation Method 2
The first resistive circuit is coupled to the first doped well in series, wherein when the switching circuit is controlled to electrically disconnect the signal node from the first amplifying circuit and the voltage level of the signal node reaches a second predetermined voltage level, the first resistive circuit is arranged to limit a current flowing into the first doped well
Data Source
AI summary
A switching device includes: a first switching circuit, having a control node coupled to a first control signal, and arranged to selectively couple a signal node to a first amplifying circuit according to the first control signal; and a first control circuit, having a first control node and a second control node coupled to the control node of the first switching circuit and the signal node, respectively, wherein when the first switching circuit is controlled to electrically disconnect the signal node from the first amplifying circuit and a voltage level of the signal node reaches a first predetermined voltage level, the first control circuit is arranged to make the control node of the first switching circuit electrically connected to the signal node.