Gate-Connected RF Switch Linearizer for Harmonic Distortion
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Solution Overview
Problem
Non-linearities in communication device switching circuits cause harmonic and intermodulation distortion, leading to interference challenges in maintaining signal isolation and insertion loss, particularly in multichannel communication equipment.
Innovation Solution
A radio-frequency switch design incorporating a switch arm and a linearizer arm, where the linearizer arm compensates for non-linearity effects by generating distortion products of opposite phase to cancel out those generated by the switch arm, using transistors connected to the gate or body of the switch arm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a switch arm with transistors is used to route radio-frequency signals, then signal routing functionality is achieved, but non-linearity effects cause harmonic and intermodulation distortion
Solution Approach 1:
The switch is divided into separate arms (switch arm and linearizer arm), each with specific transistors dedicated to particular functions. This segmentation allows the linearizer arm to independently compensate for non-linearities generated by the switch arm without interfering with the primary switching function.
Solution Approach 2:
The linearizer arm intentionally generates distortion products that are opposite in phase to those generated by the switch arm. By converting the harmful non-linearity effect into a beneficial cancellation mechanism, the overall distortion is reduced while maintaining signal routing functionality.
2Reliability
If multiple transistors are used in the switch arm to handle different signal paths, then signal isolation between channels is improved, but non-linearity effects increase causing more distortion
Solution Approach 1:
The linearizer arm provides a feedback mechanism by monitoring and compensating for the non-linearities generated by the switch arm. The distortion products generated by the linearizer arm are fed back to cancel out the harmful intermodulation distortion, maintaining signal isolation while reducing overall distortion.
Solution Approach 2:
The switch incorporates a composite structure with two different transistor configurations - the switch arm transistors optimized for signal routing and isolation, and the linearizer arm transistors optimized for distortion compensation. This composite approach allows both high signal isolation and low distortion to coexist.
3Power
If the gate width of transistors is increased to improve signal handling capability, then power handling is improved, but non-linearity effects become more pronounced
Solution Approach 1:
The patent employs different gate width parameters for transistors in the switch arm versus those in the linearizer arm. By optimizing these parameters differently, the switch arm can handle high power while the linearizer arm compensates for the resulting non-linearities, achieving both high power handling and low harmonic distortion.
Data Source
AI summary
Circuits, systems, and methods to compensate for non-linearities associated with a switching circuit are discussed herein. For example, a switch circuit can include a switch arm and a linearizer arm. The switch arm can have a first transistor connected between an input node and an output node. The switch arm can be configured to receive a radio-frequency signal. The linearizer arm can have a second transistor connected to at least one of a gate or a body of the first transistor. The linearizer arm can be configured to compensate a non-linearity effect generated by the switch arm.