Single-Ended to Differential Amplifier Feedback for Even-Order Distortion

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Solution Overview

Problem

Conventional active baluns introduce distortion and unfavorable power dissipation when converting single-ended signals to differential signals, and passive baluns are costly and unsuitable for wide bandwidth applications.

Innovation Solution

An amplifier system that includes a converter for generating an amplified differential signal and a compensator to extract and adjust a distortion compensating signal, which is fed back to cancel even order distortion, maintaining a loop gain of zero and ensuring linearity between the single-ended and differential signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional active baluns are used to convert single-ended signals to differential signals, then signal conversion is achieved, but distortion is introduced and power dissipation increases

Engineering Contradiction:

Improvesignal conversion capabilityVSAvoiddistortion

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the differential output signal is fed back through a feedback network to generate a compensating signal. This feedback signal is combined with the input signal to cancel out the even-order distortion components generated by the non-linear converter, thereby resolving the contradiction between achieving signal conversion and avoiding distortion

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent converts the harmful distortion effect into a useful compensating signal. By extracting the even-order distortion components from the converter output and processing them through the feedback network, the system generates a signal that, when combined with the input, actively cancels the distortion, thus transforming the harmful effect into a beneficial correction

Inventive Principle:

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

2Ease of manufacture

If conventional active baluns are used to convert single-ended signals to differential signals, then signal conversion is achieved, but power dissipation increases

Engineering Contradiction:

Improvesignal conversion capabilityVSAvoidpower dissipation

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent segments the signal processing function into distinct components: a non-linear converter that performs the difficult single-ended to differential conversion, and a separate feedback network that handles distortion compensation. This segmentation allows the converter to operate without requiring excessive power for linearization, as that function is handled separately by the feedback mechanism

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The feedback network acts as an intermediary that mediates between the non-linear converter and the final output. It processes the converter output, extracts distortion components, and generates compensating signals that are combined with the input, thereby reducing the power requirements of the converter itself while maintaining signal conversion capability

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If passive baluns are used for signal conversion, then distortion is reduced, but cost increases and bandwidth is limited

Engineering Contradiction:

ImprovedistortionVSAvoidcost and bandwidth limitation

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/passive balun structure with an active electronic conversion circuit combined with an electronic feedback control system. This substitution enables wide bandwidth operation and flexible integration while maintaining low distortion through the electronic distortion cancellation mechanism, thereby resolving the limitations of passive baluns

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8587381B1Even order distortion cancellation in single-ended input, differential output amplifiers using feed-back

Publication Date: 2013.11.19 MARVELL ASIA PTE LTD

AI summary

An amplifier and a method are provided for converting a single ended signal to an amplified differential signal. The amplifier comprises an input configured to receive a single ended signal, a differential amplifier that outputs an amplified differential signal based on the single ended signal, and a compensator coupled to the differential amplifier and configured to inject an adjusted distortion compensating signal based on the even order distortion signal to compensate for a distortion in the amplified differential signal. The method comprises receiving a single ended signal, converting the single ended signal to an amplified differential signal, and generating a distortion compensating signal to substantially cancel an even order distortion signal injected to the differential signal by the converting.