Polycrystalline Resistor Non-Linearity Compensation via Segmentation

Solution Overview

Problem

Polycrystalline resistors in analog integrated circuits exhibit non-linearity due to electric field effects, which existing compensation methods only partially address, leading to inefficiencies and increased cost due to die area and power consumption.

Innovation Solution

Segmenting polycrystalline resistors into multiple segments and applying electric fields of opposite polarities to each segment, using third terminals to offset impedance variations, resulting in a linear cumulative resistance to a first-order approximation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional compensation methods (metallization layer or bootstrapped resistor) are used to reduce non-linearity of polycrystalline resistors, then non-linearity is partially compensated, but die area and power consumption increase

Engineering Contradiction:

Improvelinearity of resistanceVSAvoiddie area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The polycrystalline resistor is divided into multiple resistive segments (first and second segments) with different non-linearity characteristics. Each segment experiences different electric field effects, and their combined resistance provides better overall linearity compensation without requiring additional compensation structures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the electrical parameters (voltage potentials) at different terminals to create controlled electric fields across the resistive segments. By adjusting the potentials at terminals 308a and 308b relative to terminals 302a and 302b, the electric field distribution is optimized to compensate for non-linearity while maintaining compact layout.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If conventional compensation methods (metallization layer or bootstrapped resistor) are used to reduce non-linearity of polycrystalline resistors, then non-linearity is partially compensated, but power consumption increases

Engineering Contradiction:

Improvelinearity of resistanceVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The polycrystalline resistor is divided into multiple resistive segments (first and second segments) with different non-linearity characteristics. Each segment experiences different electric field effects, and their combined resistance provides better overall linearity compensation without requiring additional compensation structures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The resistive segments themselves provide the compensation function through their inherent non-linear characteristics and the electric fields applied across them. No separate compensation circuitry or additional active elements are required, eliminating the power consumption associated with buffer drivers and control circuits in conventional approaches.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If bootstrapped resistor design is used to substantially cancel field effect, then non-linearity is compensated, but well width and well-to-well distance must be large increasing die area

Engineering Contradiction:

Improvelinearity of resistanceVSAvoidwell width and well-to-well distance

Core Design Contradiction:

Measurement precisionVSLength of moving object

Solution Approach 1:

The polycrystalline resistor is divided into multiple resistive segments (first and second segments) with different non-linearity characteristics. Each segment experiences different electric field effects, and their combined resistance provides better overall linearity compensation without requiring additional compensation structures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention applies electric fields in a different dimensional configuration compared to conventional bootstrapped resistors. By using third terminals (308a, 308b) that can be positioned adjacent to the resistive segments and applying voltages relative to the main terminals, the electric field is applied in a manner that does not require increased well width or well-to-well distance.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

Significantly compensates for non-linearity in resistive circuits, achieving up to 90% reduction in non-linearity, while optimizing die area and power usage.

Implementation Method 1

the resistance of polycrystalline silicon (also referred to as polysilicon, poly-Si or simply poly) varies with the applied voltage in a non-linear fashion in the presence of an electric field. This non-linearity is caused by an accumulation of carriers (and thus reduced resistance) in the presence of a positive electric field, or conversely, by a depletion of carriers (and thus increased resistance) in the presence of a negative electric field.

Methodology Applied

Scientific EffectField effect: Electric Field

Data Source

PatentUS7915995B2Compensation of field effect on polycrystalline resistors

Publication Date: 2011.03.29 CIRRUS LOGIC INC

AI summary

A resistive circuit includes a first terminal and a second terminal and polycrystalline first and second resistive segments coupled between the first and second terminals. A third terminal A is coupled to the first resistive segment, and a third terminal B is coupled to the second resistive segment. The third terminal A has a first voltage with respect to the first terminal, and the third terminal B has a second voltage with respect to the second terminal. With this arrangement, the non-linearity of resistance of the first resistive segment at least partially compensates for non-linearity of resistance of the second resistive segment.