Active Balun Circuit for Even-Order Distortion Cancellation
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Solution Overview
Problem
Conventional balun circuits are bulky and difficult to integrate into electronic devices, and active balun circuits suffer from poor second-order linearity, limiting their applications due to high distortion.
Innovation Solution
An active balun circuit comprising a first single-to-differential circuit, a second single-to-differential circuit, and a combining circuit that generates a combined signal by summing or subtracting signals to cancel even-order distortion, allowing for high linear signal transformation between differential and single-end signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive balun circuit is fabricated using two conducting coils, then the signal transformation function is achieved, but the circuit becomes bulky and difficult to integrate into electronic devices
Solution Approach 1:
The patent replaces the mechanical coil-based passive balun structure with an active circuit implementation using transistors, resistors, and capacitors. This substitution eliminates the need for bulky conducting coils while achieving the same signal transformation function, thereby reducing circuit size and enabling integration into electronic devices.
Solution Approach 2:
The patent changes the fundamental operating parameters from passive inductive coupling in coils to active transistor-based signal processing. By using differential amplifiers and active components, the circuit achieves balun functionality with significantly reduced physical dimensions suitable for integration.
2Volume of moving object
If an active balun circuit is used to reduce size, then integration becomes feasible, but second-order linearity deteriorates resulting in high distortion
Solution Approach 1:
The patent divides the signal processing into separate differential circuits that handle different signal components. By segmenting the transformation process into distinct stages with specific functions, the circuit maintains high linearity while achieving compact size through active components.
Solution Approach 2:
The patent employs asymmetric circuit configurations in the differential stages to compensate for non-linearities. By introducing controlled asymmetries in the active component arrangements, the circuit achieves improved second-order linearity and reduced distortion while maintaining compact dimensions.
3Ease of manufacture
If conventional active balun circuits are used for signal transformation, then circuit integration is achieved, but distortion increases due to poor second-order linearity
Solution Approach 1:
The patent incorporates feedback mechanisms in the active balun circuit to correct non-linear distortions. By monitoring output signals and adjusting operating parameters through feedback loops, the circuit maintains high linearity and reduces second-order distortion while remaining integrated and manufacturable.
Solution Approach 2:
The patent introduces intermediary compensation circuits that actively counteract distortion effects. These intermediary stages process signals to eliminate second-order harmonics before final output, thereby reducing distortion while maintaining integration and ease of manufacture.
Data Source
AI summary
A signal converting circuit includes: a first single-to-differential circuit arranged to generate a first signal having a first polarity and a second signal having a second polarity different from the first polarity; a second single-to-differential circuit arranged to generate a third signal having the second polarity and a fourth signal having the first polarity; and a combining circuit arranged to generate a first combined signal having the first polarity according at least two signals from the first signal, the second signal, the third signal, and the fourth signal, and output an output signal according to at least the first combined signal.