Source Follower Bias Circuit for Varactor Leakage Compensation

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Solution Overview

Problem

Higher leakage currents in varactors require higher refresh rates and larger storage capacitors to maintain bias voltage within a specific range, posing obstacles for commercialization.

Innovation Solution

Incorporating a tunable component and a first source follower circuit with transistors to compensate for leakage currents, maintaining bias voltage effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If higher refresh rates or larger storage capacitors are used to compensate for leakage current, then bias voltage stability is improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvebias voltage stabilityVSAvoidcircuit complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where the source follower circuit continuously monitors the bias voltage at the circuit node and automatically adjusts the voltage output to compensate for leakage current effects. This closed-loop control maintains bias voltage stability without requiring larger capacitors or higher refresh rates, thereby resolving the contradiction between voltage stability and device complexity

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The source follower circuit performs self-compensation by using its own output to maintain the bias voltage at the circuit node. The circuit automatically detects voltage drops caused by leakage and replenishes them through the source follower action, eliminating the need for external intervention or complex refresh mechanisms

Inventive Principle:
Principle #25Self-service

2Stability of the object's composition

If higher refresh rates are used to compensate for leakage current, then bias voltage is maintained within range, but power consumption increases

Engineering Contradiction:
Improvebias voltage stabilityVSAvoidpower consumption
Core Design Contradiction:
Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The source follower circuit provides continuous voltage compensation rather than periodic refresh operations. By maintaining a continuous corrective action that smoothly counteracts leakage current effects, the circuit achieves bias voltage stability without the energy-intensive periodic refresh cycles, thereby reducing power consumption while maintaining voltage within the required range

Inventive Principle:
Principle #20Continuity of useful action

3Stability of the object's composition

If larger storage capacitors are used to compensate for leakage current, then bias voltage stability is improved, but device area increases

Engineering Contradiction:
Improvebias voltage stabilityVSAvoiddevice area
Core Design Contradiction:
Stability of the object's compositionVSArea of stationary object

Solution Approach 1:

The patent replaces the passive capacitive storage mechanism with an active source follower voltage regulation mechanism. Instead of relying on larger physical capacitors to store charge and maintain voltage, the source follower circuit actively regulates the bias voltage through transistor action, achieving the same stability effect with significantly reduced device area

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP4152614B1Electronic device
Publication Date: 2026.04.08 INNOLUX CORP
  • EP4152614B1 patent drawingFigure 1
  • EP4152614B1 patent drawingFigure 2
  • EP4152614B1 patent drawingFigure 3

AI summary

An electronic device (100, 300, 500, 700, 900, 1000, 1100, 1200) is provided. The electronic device (100, 300, 500, 700, 900, 1000, 1100, 1200) includes a tunable component (120, 320, 520, 720,920, 1020, 1120, 1220) and a first source follower circuit(111,311,511, 711, 911, 1011, 1111_1, 1111_2, 1211). The tunable component (120, 320, 520, 720, 920, 1020, 1120, 1220) is electrically connected to a circuit node (N1, N2). The first source follower circuit (111, 311, 511, 711, 911, 1011, 1111_1, 1111_2, 1211) is electrically connected to the circuit node (N1, N2). The first source follower circuit (111, 311, 511, 711, 911, 1011, 1111_1, 1111_2, 1211) includes a first control terminal and a first terminal. The first control terminal is electrically connected to the first terminal.