Switchless Degeneration Matrix for Variable-Gain Amplifier Linearity

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Solution Overview

Problem

Wireless communication devices face reduced performance in gain modes due to impaired linearity and noise figure (NF) in signal amplifiers, particularly in variable-gain stages where switches are used for degeneration switching, leading to increased size and control logic complexity.

Innovation Solution

A degeneration matrix is employed in signal amplifiers without switches, providing tailored impedances based on gain modes and paths, reducing die size, improving NF, and enhancing linearity by eliminating switch-related losses and control logic.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If switches are used for degeneration switching in variable-gain stages, then gain modes can be switched, but linearity and noise figure deteriorate

Engineering Contradiction:

Improvegain modes switchingVSAvoidlinearity and noise figure

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent extracts and removes the switches from the degeneration switching mechanism. Instead of using switches to select different degeneration inductors, the invention uses a switchless architecture where the degeneration inductor is directly connected to the variable-gain stage, eliminating the harmful switching action while preserving gain mode adaptability through alternative means.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent inverts the conventional approach by making the degeneration inductor value variable while keeping the connection continuous (without switches). The variable-gain stage controls the effective degeneration through its own switching action on the feedback path, rather than using external switches to select fixed degeneration values.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If switches are used for degeneration switching, then gain modes can be switched, but device size increases

Engineering Contradiction:

Improvegain modes switchingVSAvoiddie size

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent removes the switch components and their associated control logic from the degeneration switching path. This extraction eliminates the need for multiple switch devices, reducing the overall die area required for the variable-gain amplifier while maintaining the ability to switch between gain modes.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The variable-gain stage performs multiple functions: it provides gain control and simultaneously controls the effective degeneration through its switching action on the feedback path. This multi-functionality eliminates the need for separate switch components dedicated to degeneration switching, reducing device size.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If switches are used for degeneration switching, then gain modes can be switched, but control logic complexity increases

Engineering Contradiction:

Improvegain modes switchingVSAvoidcontrol logic

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the control logic for degeneration switching from the overall control system. By making the degeneration inductor directly connected and controlled by the variable-gain stage's inherent switching action, the patent eliminates the need for separate control logic circuits that would otherwise be required to coordinate switch operation with gain mode selection.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the degeneration control function with the variable-gain stage's existing control mechanism. The same control signals that switch the gain modes also control the effective degeneration through the feedback path switching, consolidating control functions and reducing overall control logic complexity.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20250337381A1Gain stage degeneration inductor switching without the use of switches

Publication Date: 2025.10.30 SKYWORKS SOLUTIONS INC

AI summary

Disclosed herein are signal amplifier architectures that provide a plurality of gain modes. Different gain modes can use different paths through the amplifier architecture. Switches that are used to select the path through the amplifier architecture can be configured to also provide targeted impedance in a degeneration block or matrix. The switches that select the gain path are provided in the amplifier architecture and are thus not needed or used in the degeneration block, thereby reducing the size of the package for the amplifier architecture, improving the noise figure (NF), improving impedance matching, and eliminating the need for control logic associated with the degeneration block or matrix.