Cross-Coupled Multi-Band LNA for Inter-Band Interference Cancellation

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Solution Overview

Problem

Multi-band low noise amplifiers for wireless devices face challenges with increased die area and cost due to large transistor cores, and inter-band interference across different frequency bands decreases throughput for wireless local area networks.

Innovation Solution

The design incorporates dual-band and tri-band low noise amplifiers with cascoded transistors and tunable LC circuits, along with cross-coupled circuits that phase-shift and cancel interference between frequency bands, reducing inter-band interference and enhancing throughput.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple low noise amplifiers are used for multi-band reception, then signal reception capability across different frequency bands is improved, but die area and chip size increase

Engineering Contradiction:

Improvemulti-band reception capabilityVSAvoiddie area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent combines multiple low noise amplifier functions into a single integrated circuit that can operate across multiple frequency bands (2.4 GHz and 5.6 GHz). The shared transistor core and common input stage merge what would traditionally require separate amplifier circuits, reducing die area while maintaining multi-band reception capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The low noise amplifier is designed with universal functionality to handle multiple frequency bands through a single device. The amplifier core can be configured to operate at different frequencies by adjusting the resonant circuits, eliminating the need for separate dedicated amplifiers for each band.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple low noise amplifiers are used for multi-band reception, then signal reception capability across different frequency bands is improved, but cost increases

Engineering Contradiction:

Improvemulti-band reception capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If simultaneous multi-band signals are received, then wireless device functionality is enhanced, but inter-band interference decreases throughput

Engineering Contradiction:

Improvesimultaneous multi-band operationVSAvoidthroughput

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent extracts and removes inter-band interference from the received signals using interference cancellation circuits. These circuits identify and subtract the interfering signals from one frequency band from the desired signals in another band, eliminating the harmful interference that would otherwise reduce throughput.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful inter-band interference into useful information by using the interfering signals as inputs to cancellation circuits. The interference signals are processed and subtracted from the desired signals, transforming the harmful effect into a benefit that enables clean simultaneous multi-band reception.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Reliability

If large transistor cores are used in low noise amplifiers, then amplification performance is improved, but die area increases

Engineering Contradiction:

Improveamplification performanceVSAvoiddie area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent optimizes the transistor core size and characteristics specifically for the required amplification performance rather than using uniformly large transistors. The design uses appropriately sized transistors only where needed for noise figure and gain requirements, while other parts of the circuit use smaller components, achieving good amplification performance with minimized overall die area.

Inventive Principle:

Principle #3Local quality

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

This approach reduces inter-band interference, thereby improving the amplification efficiency and throughput for multi-band signals, particularly for systems adhering to IEEE 802.11 WiFi standards, while minimizing the physical size and cost of the amplifiers.

Implementation Method 1

cross-coupled circuits that phase-shift and cancel interference between frequency bands

Methodology Applied

Scientific EffectPhase shift:

Implementation Method 2

cross-coupled circuits that phase-shift and cancel interference between frequency bands

Methodology Applied

Scientific EffectDestructive interference: Interference

Implementation Method 3

tunable LC circuits

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentEP3189588B1Multi-band low noise amplifier

Publication Date: 2020.04.22 QUALCOMM INC

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AI summary

An apparatus (300) includes a first path tuned to a first frequency band and a second path tuned to a second frequency band. The apparatus (300) also includes cross-coupled circuitry (390) having a first input (314) coupled to the first path and a second input (316) coupled to the second path and having a first output (336) coupled to the second path and a second output (328) coupled to the first path.