Equalizer Circuit Using Negative Impedance for Adjustable DC Gain

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional equalizers in semiconductor circuits, used to compensate for signal decay during high-frequency operations in USB communication, are limited by their reliance on resistor-capacitor (RC) networks, which restricts the adjustment of direct current (DC) gain and bandwidth, and require complex pole structures that are difficult to control.

Innovation Solution

The integration of a differential amplifier with a circuit that provides negative impedance, eliminating the need for an RC network, allowing for adjustable DC gain and bandwidth through the adjustment of current sources and transconductance, thereby enhancing signal boosting capabilities during high-frequency operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional RC networks are used in equalizers, then signal decay compensation is achieved, but DC gain and bandwidth adjustment is restricted and circuit complexity increases

Engineering Contradiction:

ImproveDC gain and bandwidth adjustabilityVSAvoidcircuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the fundamental parameters of the equalizer circuit by replacing RC networks with negative impedance circuits. This allows DC gain to be controlled by transconductance parameters (gm) and bandwidth by resistance parameters, providing continuous adjustability without the discrete pole-zero constraints of RC networks. The negative impedance circuit enables independent control of gain and bandwidth through current source adjustment.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes the traditional passive RC network mechanism with an active negative impedance circuit mechanism. Instead of relying on resistor-capacitor time constants to define poles and zeros, the invention uses transconductance amplifiers and negative impedance elements to achieve the same equalization function with superior controllability and reduced complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Speed

If RC networks are used to compensate signal decay, then high-frequency operation is supported, but complex pole structures that are difficult to control are introduced

Engineering Contradiction:

Improvehigh-frequency operation capabilityVSAvoidpole structure control difficulty

Core Design Contradiction:

SpeedVSDifficulty of detecting and measuring

Solution Approach 1:

The patent transforms the pole structure from complex (requiring multiple RC stages) to simple (single real pole) by using negative impedance circuits. The real pole frequency is directly controlled by the resistance parameter of the negative impedance circuit, making it easily measurable and adjustable without dealing with complex conjugate poles that are difficult to characterize and control.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If DC gain is increased to boost signals during high-frequency operation, then signal decay compensation improves, but circuit complexity and control difficulty increase

Engineering Contradiction:

Improvesignal decay compensation effectivenessVSAvoidcircuit control complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent enables independent control of DC gain through transconductance parameters without affecting the real pole frequency. This is achieved by adjusting the current sources in the negative impedance circuit, which changes the transconductance and thus the DC gain, while the bandwidth remains determined by the resistance parameter. This decoupling simplifies control compared to RC networks where gain and bandwidth are coupled through component values.

Inventive Principle:

Principle #35Parameter changes

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 enables efficient signal boosting and adjustable bandwidth by modifying the DC gain and real pole frequencies, improving the integrated circuit's performance without the complexity of RC networks, leading to enhanced high-frequency signal compensation.

Implementation Method 1

The circuit can provide a negative impedance to the differential amplifier. By adjusting the negative impedance, a direct current (DC) gain of the integrated circuit can be changed.

Methodology Applied

Scientific EffectNegative impedance:

Data Source

PatentUS7961050B1Integrated circuits including an equalizer and operating methods thereof

Publication Date: 2011.06.14 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An integrated circuit includes a differential amplifier. The differential amplifier includes at least one output end. A circuit is coupled with the at least one output end of the differential amplifier. The circuit does not include a resistor-capacitor (RC) network and is configured for providing a negative impedance to the differential amplifier for adjusting a direct current (DC) gain of the integrated circuit.