Poly-Resistor Impedance Circuit for Depletion Effect Suppression

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Solution Overview

Problem

The depletion effect in poly-silicon resistors leads to non-linearity in electronic circuits, causing unpredictable behavior and requiring a novel solution to suppress this effect.

Innovation Solution

A differential amplifier circuit is designed with a poly-resistor comprising a poly-silicon layer, a channel layer, and an insulation layer, where dynamic control voltages are applied to the channel layer to control the resistance of the poly-silicon layer, thereby suppressing the depletion effect.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If poly-resistors with high sheet resistance values are used to reduce chip size, then area is reduced, but non-linearity increases due to depletion effect

Engineering Contradiction:
Improvechip areaVSAvoidlinearity
Core Design Contradiction:
Area of moving objectVSReliability

Solution Approach 1:

The patent changes the electrical parameters of the poly-resistor by applying control voltages to the channel layer, which modifies the resistance characteristics and suppresses the depletion effect, thereby improving linearity while maintaining high sheet resistance and small area

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The channel layer acts as an intermediary between the control voltages and the poly-silicon layer, enabling dynamic adjustment of the poly-resistor's resistance to counteract the depletion effect and improve linearity

Inventive Principle:
Principle #24Intermediary (Mediator)

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

The proposed solution effectively eliminates the depletion effect, making the poly-resistor more linear and conforming to Ohm's law, thereby improving the circuit's performance and linearity.

Implementation Method 1

the depletion effect is a phenomenon in which there is unwanted variation in the threshold voltage of devices using poly-silicon as a gate material

Methodology Applied
Scientific EffectDepletion effect:

Implementation Method 2

a resistive layer-insulator layer field effect transistor having a source region, a drain region, and a channel therebetween

Methodology Applied
Scientific EffectField effect:

Data Source

PatentEP3309850B1Impedance circuit with poly-resistor
Publication Date: 2025.04.30 MEDIATEK INC
  • EP3309850B1 patent drawingFigure 1~2
  • EP3309850B1 patent drawingFigure 3~4
  • EP3309850B1 patent drawingFigure 5A~5B

AI summary

An impedance circuit includes a poly-resistor and a controller. The poly-resistor has a first terminal and a second terminal. The controller generates a first control voltage and a second control voltage. The resistance between the first terminal and the second terminal of the poly-resistor is determined according to the first control voltage and the second control voltage. The second control voltage is different from the first control voltage. The proposed impedance circuit can improve the linearity of the poly-resistor.