Cascode Amplifier Post-Distortion Compensation for HD2 Rejection

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Solution Overview

Problem

The challenge in developing 5G wireless technologies is the need for smaller, less expensive transceivers that can handle signal distortion caused by second-harmonic distortion (HD2) without relying on large, costly off-chip filters, which are impractical for Internet of Things (IoT) devices due to size and cost constraints.

Innovation Solution

Implementing a cascode amplifier with post-distortion compensation circuitry that generates a compensation current to counteract the second-harmonic portion of the signal current, allowing for effective signal amplification while reducing distortion without the need for expensive filters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If large off-chip filters are used to reduce second-harmonic distortion, then signal quality is improved, but device size and cost increase

Engineering Contradiction:

Improvesignal qualityVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent extracts and removes the harmful second-harmonic distortion component from the amplified signal by generating a compensation current that is equal in magnitude but opposite in phase to the distortion current, thereby eliminating the need for large off-chip filters

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a compensation current as an intermediary element that mediates between the distorted signal and the desired clean signal, canceling out the second-harmonic distortion through constructive interference of currents

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If large off-chip filters are used to reduce second-harmonic distortion, then signal quality is improved, but device cost increases

Engineering Contradiction:

Improvesignal qualityVSAvoiddevice cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces expensive off-chip filters with a cost-effective integrated compensation circuit implemented using standard CMOS transistors, significantly reducing device manufacturing cost

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Power

If signal amplification is performed, then signal strength is improved, but second-harmonic distortion increases

Engineering Contradiction:

Improvesignal strengthVSAvoidsecond-harmonic distortion

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by generating a compensation current before the distorted signal is output, which preemptively counteracts the second-harmonic distortion caused by the amplification process

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent converts the harmful second-harmonic distortion into a beneficial cancellation mechanism by using the distortion current itself as the basis for generating the compensation current, thereby transforming the problem into the solution

Inventive Principle:

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

Data Source

PatentUS10541654B1Amplification with post-distortion compensation

Publication Date: 2020.01.21 QUALCOMM INC

AI summary

Amplification with post-distortion compensation is disclosed. In an example aspect, an apparatus includes a voltage rail and a cascode amplifier. The cascode amplifier includes an amplification node, a cascode node, and a common-source node. The cascode amplifier also includes at least one cascode transistor, an input transistor, and a compensation transistor. The cascode transistor is coupled between the amplification node and the cascode node. The input transistor is coupled between the cascode node and the common-source node. The compensation transistor is coupled between the voltage rail and the cascode node.