Receiver Interferer Cancellation via Dual-Path Signal Mixing

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Solution Overview

Problem

Wireless communication receivers face challenges in operating at low supply voltages (0.5-0.7 volts) while maintaining low-noise-figure and high-linearity characteristics, as existing technologies struggle to effectively cancel interferers and achieve sufficient input intercept points due to linearity bottlenecks in baseband circuits.

Innovation Solution

The implementation of a receiver architecture with two paths for processing RF signals, where one path includes a main path with a low noise amplifier and a passive mixer, and an alternate path with a programmable gain amplifier and high pass filter, allowing for interferer cancellation by matching gain and phase settings to combine signals and minimize signal power at the output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single path with low noise amplifier is used, then noise figure is improved, but linearity and interferer cancellation capability deteriorate

Engineering Contradiction:

Improvenoise figureVSAvoidinterferer cancellation capability

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The receiver is divided into two parallel signal paths: a main path with a low noise amplifier for noise-sensitive applications and an alternate path with a programmable gain amplifier for interferer cancellation. This segmentation allows each path to optimize for different functions, resolving the contradiction between noise figure and interferer cancellation capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A combiner circuit acts as an intermediary to merge the signals from the main path and alternate path. The combiner enables the system to leverage both paths simultaneously, using the alternate path to generate cancellation signals that counteract interferers while the main path provides low-noise amplification.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If baseband circuits are simplified, then device complexity is reduced, but linearity performance deteriorates

Engineering Contradiction:

Improvebaseband circuit complexityVSAvoidlinearity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The non-linearity problem is extracted from the baseband circuits and transferred to the RF domain, where it is addressed by the alternate path with programmable gain amplifier. This allows the baseband circuits to remain simple while still achieving high linearity through the RF-domain interferer cancellation mechanism.

Inventive Principle:

Principle #2Taking out (Extraction)

3Use of energy by moving object

If supply voltage is reduced, then power consumption is improved, but linearity and noise performance deteriorate

Engineering Contradiction:

Improvepower consumptionVSAvoidlinearity and noise figure

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The programmable gain amplifier in the alternate path dynamically adjusts its gain based on the detected interferer strength. This dynamic adjustment allows the system to maintain optimal linearity and noise performance across varying operating conditions while operating at reduced supply voltages, resolving the contradiction between power consumption and performance.

Inventive Principle:

Principle #15Dynamics

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 effectively cancels out interferers, improves the third-order input intercept point from -29 dBm to -12 dBm, and reduces the impact of non-linearity in baseband circuits, enabling receivers to operate efficiently at low supply voltages with enhanced linearity and noise performance.

Implementation Method 1

a first mixer in a main path that downconverts a first RF signal to form a main baseband or intermediate-frequency signal

Methodology Applied

Scientific EffectMixing:

Implementation Method 2

a second mixer in an alternate path that downconverts a second RF signal to form an alternate baseband or intermediate-frequency signal

Methodology Applied

Scientific EffectMixing:

Implementation Method 3

the main baseband or intermediate-frequency signal and the alternate baseband or intermediate-frequency signal, when combined, cancel out an interferer in the third RF signal

Methodology Applied

Scientific EffectInterference cancellation: Interference

Data Source

PatentUS8594603B2Systems and methods for cancelling interferers in a receiver

Publication Date: 2013.11.26 THE TRUSTEES OF COLUMBIA UNIV IN THE CITY OF NEW YORK

AI summary

In some embodiments, systems and methods for cancelling interferers in a receiver, comprise: a first mixer in a main path that downconverts a first RF signal to form a main baseband or intermediate-frequency signal; and a second mixer in an alternate path that downconverts a second RF signal to form an alternate baseband or intermediate-frequency signal, wherein the first RF signal and the second RF signal are both based on a third RF signal, and wherein the main baseband or intermediate-frequency signal and the alternate baseband or intermediate-frequency signal, when combined, cancel out an interferer in the third RF signal.