Variable-Resistor Attenuator With Impedance Matching for Low-Power Gain

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Solution Overview

Problem

Existing wireless communication devices face challenges in maintaining high-power mode performance while allowing for a programmable low-power mode gain and signal linearity, particularly in multi-mode-multi-band power amplifiers, which can lead to SNR degradation in low-power transmissions.

Innovation Solution

Implementing a tunable attenuator using variable resistive elements and an impedance transformation circuit to adjust impedance and gain levels, enabling high-power mode performance with minimal impact on input matching and linearity, and providing over 10 dB attenuation in low-power mode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a programmable low-power mode gain is implemented in multi-mode-multi-band power amplifiers, then signal linearity is improved, but signal-to-noise ratio degrades

Engineering Contradiction:

Improvesignal linearityVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The attenuation circuit is segmented into multiple variable resistive elements (first variable resistive element, second variable resistive element) that can be independently controlled. This segmentation allows different attenuation levels to be applied to different signal components, enabling precise control of gain in low-power mode while maintaining signal linearity without degrading SNR.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic attenuation control where the variable resistive elements can be adjusted in real-time based on operating conditions. The controller dynamically switches between high-power mode and low-power mode, and within low-power mode, dynamically adjusts the attenuation level to maintain optimal signal linearity while minimizing SNR degradation.

Inventive Principle:

Principle #15Dynamics

2Reliability

If gain is reduced in low-power mode, then signal-to-noise ratio stability is improved, but insertion loss increases

Engineering Contradiction:

Improvesignal-to-noise ratio stabilityVSAvoidinsertion loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the resistance values of the variable resistive elements based on the desired attenuation level. By precisely controlling the resistance parameters of the first and second variable resistive elements, the circuit achieves over 10 dB attenuation in low-power mode while minimizing insertion loss through optimized resistance values and impedance matching.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The impedance transformation circuit acts as an intermediary between the attenuation circuit and the rest of the amplifier system. It transforms the impedance to match the optimal load conditions, thereby reducing the impact of insertion loss while maintaining SNR stability in low-power mode.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If variable resistive elements are used for attenuation, then gain control flexibility is improved, but device complexity increases

Engineering Contradiction:

Improvegain control flexibilityVSAvoidcircuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into a single integrated attenuation circuit. The first variable resistive element, second variable resistive element, and impedance transformation circuit work together as a unified structure that provides both attenuation and impedance matching functions, reducing overall device complexity despite the use of variable resistive elements.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The attenuation circuit with variable resistive elements serves multiple functions: it provides gain control flexibility, maintains impedance matching, and enables operation in both high-power and low-power modes. This multi-functionality reduces the need for separate circuits for each function, thereby managing device complexity while achieving high adaptability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Maintains high-power mode performance with reduced gain in low-power mode, ensuring signal-to-noise ratio stability and input matching, while minimizing insertion loss and linearity effects.

Implementation Method 1

an impedance transformation circuit coupled between the first node and the second node

Methodology Applied

Scientific EffectImpedance transformation: Electrical Resistance

Implementation Method 2

an attenuation circuit including a first variable resistive element coupled between the first node and a reference potential node, and a second variable resistive element coupled between the second node and the reference potential node

Methodology Applied

Scientific EffectResistive dissipation: Joule Heating

Data Source

PatentUS12407339B2Attenuator using variable resistors

Publication Date: 2025.09.02 QUALCOMM INC

AI summary

Certain aspects of the present disclosure are directed towards a signal processing circuit. The signal processing circuit generally includes: an impedance transformation circuit coupled between a first node and a second node; and an attenuation circuit including a first variable resistive element coupled between the first node and a reference potential node, and a second variable resistive element coupled between the second node and the reference potential node.