Amplifier Feedback Network With Assist Current Source

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Transconductance amplifiers in data transmission networks require high transconductance to achieve a large signal-to-noise-plus-distortion ratio (SNDR), which is costly and power-consuming due to the need for increased amplifier width and current, especially in CMOS devices where transconductance increases with the square root of the width and current, leading to space and power efficiency issues.

Innovation Solution

The introduction of an assist current source at the output of the amplifier feedback network, which reduces the required transconductance of the amplifier by providing external current, thereby alleviating the need for high amplifier current and width, allowing for lower transconductance operation without significant loss in SNR or SNDR.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the transconductance of the amplifier is increased to achieve a large signal-to-noise-plus-distortion ratio (SNDR), then the SNDR is improved, but the power consumption and device cost increase due to the need for increased amplifier width and current

Engineering Contradiction:

Improvesignal-to-noise-plus-distortion ratio (SNDR)VSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent divides the current requirement into two separate functions: the amplifier provides current for signal amplification, while a dedicated assist current source provides the additional current needed to maintain high transconductance. This segmentation allows the amplifier to operate at lower current and power consumption while the assist current source supplements the transconductance requirement, resolving the contradiction between SNDR and power consumption

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The assist current source acts as an intermediary element that mediates between the amplifier and the load. It provides the additional current needed to maintain high effective transconductance without requiring the amplifier itself to consume high power. This intermediary current source enables the amplifier to achieve high SNDR performance while operating at lower power levels

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the transconductance of the amplifier is increased to achieve a large signal-to-noise-plus-distortion ratio (SNDR), then the SNDR is improved, but the device cost and die space increase due to the need for increased amplifier width

Engineering Contradiction:

Improvesignal-to-noise-plus-distortion ratio (SNDR)VSAvoidamplifier width and die space

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent segments the transconductance function between the amplifier (which maintains a moderate, area-efficient width) and the assist current source (which provides the additional transconductance current). This allows the amplifier to be designed with a smaller, more area-efficient width while still achieving high SNDR through the combined effect of the amplifier current and assist current

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The assist current source serves as an intermediary that provides the additional transconductance current without requiring the amplifier to increase its width. This enables high SNDR performance to be achieved while keeping the amplifier area small, as the assist current source provides the supplementary current needed for high transconductance operation

Inventive Principle:

Principle #24Intermediary (Mediator)

3Power

If the amplifier current is increased to increase the transconductance, then the transconductance is improved, but the power consumption increases leading to greater battery drain in portable devices

Engineering Contradiction:

ImprovetransconductanceVSAvoidbattery drain

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The patent segments the power consumption function: the amplifier operates at a lower, more power-efficient current level, while the assist current source provides the additional current needed for high transconductance. This segmentation allows the system to achieve high transconductance power levels without proportionally increasing the amplifier's power consumption and battery drain

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The assist current source acts as an intermediary that provides the additional current needed for high transconductance without requiring the amplifier to consume high power. This enables the system to achieve high transconductance while maintaining lower overall power consumption and reducing battery drain in portable devices

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7323931B2System and method for operating a feedback network

Publication Date: 2008.01.29 APPLE INC

AI summary

A method and apparatus are provided for operating a feedback network (300, 400). The method and apparatus operate to combine (240) a feedback signal (IF) and an incoming signal (VIN) to generate an adjusted signal (IADJ) at an input node of an amplifier element (110); amplifying the amplifier input signal in the amplifier element to produce an amplifier output signal (VOUT) at an output node of the amplifier element; processing the amplifier output signal according to a feedback operation (230) to generate the feedback signal (IF); and providing an assist current (350, 450, IASSIST) to the output node of the amplifier element, separate from an output current provided by the amplifier element.