Differential Amplifier Triode Feedback for Third-Order Linearity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing differential amplifiers face challenges in reducing third harmonic distortion and addressing issues of power consumption, robustness, and cost, particularly in achieving effective linearization.
Innovation Solution
The implementation of a differential amplifier with a non-linear feedback structure that uses non-linear devices connected between signal points and a common centre node, allowing feedback from output signals to affect the output stages, thereby reducing third order nonlinearity through the operation of transistors in the triode region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a non-linear feedback structure is provided to reduce third harmonic distortion, then linearity is improved, but device complexity increases
Solution Approach 1:
The patent implements linearization by providing feedback of output signals through non-linear elements (first and second non-linear devices) that affect output stages of the amplifier. The non-linear devices are connected between signal points of input branches and a common centre node, with control nodes receiving inverted outputs from differential output terminals. This feedback mechanism reduces third order nonlinearity by counteracting distortion through the non-linear characteristic of the feedback path.
Solution Approach 2:
The patent changes the operating parameters of the non-linear devices by connecting them in a specific configuration where they operate in the triode region. The control nodes of the non-linear devices are connected to inverted differential output terminals, and the common centre node is connected to control nodes of transistors in the output stages, effectively changing the electrical parameters to achieve linearization.
2Manufacturing precision
If non-linear devices are added to reduce third order nonlinearity, then manufacturing precision is improved, but chip area increases
Solution Approach 1:
The patent merges the non-linear feedback function with the existing amplifier structure by integrating the first and second non-linear devices into the differential circuitry. The non-linear devices share a common centre node connection, and their control nodes are connected to the same differential output terminals, consolidating the linearization function within the existing chip area rather than adding separate external components.
Solution Approach 2:
The non-linear devices serve multiple functions: they provide the non-linear feedback path for linearization, connect to the common centre node for signal routing, and receive control signals from the differential output terminals. This multi-functionality reduces the need for additional dedicated components, thereby minimizing chip area increase.
3Manufacturing precision
If feedback circuitry is implemented to improve linearity, then manufacturing precision is improved, but power consumption increases
Solution Approach 1:
The patent applies local quality by implementing the non-linear feedback only at specific critical points in the amplifier circuit - at the output stages where third order nonlinearity is most pronounced. The non-linear devices are selectively placed to affect only the output stages, rather than applying feedback throughout the entire amplifier, thereby minimizing unnecessary power consumption in non-critical areas.
Data Source
AI summary
A differential amplifier comprises a first differential circuitry structure including a first part comprising at least one branch of transistors and a second part comprising at least one branch of transistors, and a second circuitry structure. The second circuitry structure has a first non-linear device and a second non-linear device. The non-linear devices each comprise a transistor having a control node connected to a differential output terminals of the differential amplifier. A common center node of the non-linear devices is connected to a control node of one of the transistors of each branch of the first part having a differential output terminal. Amplifier applications, communication devices and network nodes are also disclosed.