RF Amplifier Input Impedance Compensation Across Gain Modes

Solution Overview

Problem

In RF amplifiers, impedance mismatches across different gain modes lead to performance degradation, including unwanted return loss and signal reflection, which existing technologies fail to adequately address.

Innovation Solution

A signal amplifier with a compensation stage featuring switchable variable resistance, configured to provide targeted adjustments to input impedance, ensuring a constant impedance across various gain settings by using switchable variable resistance branches and band selection switches, thereby minimizing impedance mismatches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a variable-gain stage is used to provide multiple gain levels, then gain versatility is improved, but input impedance varies causing return loss and signal reflection

Engineering Contradiction:

Improvegain levelsVSAvoidinput impedance stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the resistance parameter of the compensation stage by switching between different resistance values (first resistance value and second resistance value) corresponding to different gain modes. This allows the input impedance to be adjusted and maintained at a constant value across multiple gain levels, resolving the contradiction between gain versatility and impedance stability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The compensation stage acts as an intermediary between the signal source and the variable-gain stage. It mediates the impedance mismatch caused by gain changes by providing compensating resistance, thereby maintaining constant input impedance while allowing the gain stage to operate at different gain levels

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If gain mode changes are implemented, then adaptability is improved, but impedance mismatch increases causing power loss

Engineering Contradiction:

Improvegain mode switchingVSAvoidpower loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent changes the resistance parameter of the compensation stage by switching between different resistance values (first resistance value and second resistance value) corresponding to different gain modes. This allows the input impedance to be adjusted and maintained at a constant value across multiple gain levels, resolving the contradiction between gain versatility and impedance stability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The compensation stage acts as an intermediary between the signal source and the variable-gain stage. It mediates the impedance mismatch caused by gain changes by providing compensating resistance, thereby maintaining constant input impedance while allowing the gain stage to operate at different gain levels

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10985722B2Amplifying signals using compensating impedances to improve return loss and mismatch over gain modes

Publication Date: 2021.04.20 SKYWORKS SOLUTIONS INC

AI summary

Disclosed herein are methods for amplifying a signals. The methods include receiving signals at a plurality of input nodes. The methods also include configuring a gain stage to be in a selected one of a plurality of gain settings, at least some of the gain settings resulting in different impedances presented to the signal. The methods also include adjusting the resistance presented to the signal by the gain stage for the selected gain setting, the adjusted resistance being configured to provide a targeted constant value of the impedance at the input across the plurality of gain settings. The methods also include amplifying at least a portion of the received signals. Adjusting the resistance compensates for changes to the input impedance to improve return loss and mismatch over gain modes.