RF Linearizer Circuit Using Parallel Capacitors to Cut IMD3
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Solution Overview
Problem
Nonlinearities in radio frequency (RF) circuits, particularly in power amplifier systems, lead to intermodulation distortion (IMD), which degrades signal quality and increases susceptibility to interference, especially in multi-band and multi-mode wireless communication systems.
Innovation Solution
Incorporating a linearizer circuit with parallel capacitors having opposite third-order derivatives of charge with respect to voltage, or a switch circuit with a field effect transistor and a capacitor in parallel, to offset nonlinearities and reduce IMD by balancing their third-order derivatives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If switches are used in RF amplification and transmission, then signal routing and amplification are enabled, but nonlinearity occurs leading to harmonic distortion
Solution Approach 1:
A linearizer circuit is introduced as an intermediary component between the switch and the output to compensate for the nonlinearities generated by the switch. The linearizer uses capacitors with specific third-order derivative characteristics to cancel out the harmonic distortion produced by the switch during RF signal amplification and transmission.
Solution Approach 2:
The patent utilizes capacitors with specifically engineered third-order derivative of charge with respect to voltage parameters. By selecting capacitors whose third-order derivatives have opposite signs, the system can balance and cancel nonlinear effects while maintaining the switching functionality.
2Manufacturing precision
If linearizer circuits are added to reduce nonlinearity, then harmonic distortion is reduced, but device complexity increases
Solution Approach 1:
Instead of adding complex active compensation circuits, the invention achieves linearity improvement by carefully selecting passive capacitor components with specific third-order derivative parameters. This approach reduces circuit complexity while maintaining the linearizing function through precise component characterization.
Solution Approach 2:
The patent extracts and compensates for the specific nonlinear component (third-order derivative effects) separately from the main switching circuit. By isolating and addressing only the problematic third-order nonlinearities rather than attempting to linearize the entire circuit, the solution minimizes added complexity.
Data Source
AI summary
The present disclosure relates to a radio frequency circuit comprising a linearizer circuit. The linearizer circuit may comprise a first capacitor and a second capacitor arranged in parallel. The first capacitor may have a positive third order derivative of charge with respect to voltage. The second capacitor may have a negative third order derivative of charge with respect to voltage. Related radio frequency modules and wireless communication devices are also disclosed.