Capacitance Amplification Circuit With DC Behavior and Smaller Die Area
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Solution Overview
Problem
Capacitors require significant die areas and complex circuitry to achieve increased capacitance values, which are difficult to adjust and do not exhibit direct current behavior typical of a capacitor.
Innovation Solution
A capacitance circuit with a current source structure, transistors, and a capacitance amplification circuit to provide an increased capacitance based on core capacitance and amplification factor, ensuring DC behavior by compensating current at the input terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional capacitors are used to achieve increased capacitance values, then the capacitance is improved, but the die area occupied is significantly increased
Solution Approach 1:
The patent transforms the physical capacitor into an equivalent circuit model using transistors and controlled current sources. By changing the representation from a physical component to an active circuit with specific current control parameters, the system achieves high capacitance values without proportionally increasing die area, as the active components occupy less space than equivalent physical capacitors would require
Solution Approach 2:
The patent replaces the physical capacitor (mechanical/electrical component) with an electronic circuit system comprising transistors, current sources, and control circuits. This substitution allows the system to emulate capacitor behavior through controlled current injection and voltage tracking, achieving the same electrical function with reduced physical footprint
2Quantity of substance
If complex circuitry is used to provide increased capacitance values, then the capacitance is improved, but the device complexity is increased
Solution Approach 1:
The transistor Q1 serves multiple functions simultaneously: it acts as the primary switching element, provides current amplification through its gain characteristic, and enables the capacitance multiplication effect. This multi-functionality reduces the need for separate dedicated components for each function, thereby reducing overall circuit complexity while achieving high capacitance values
Solution Approach 2:
The patent employs feedback mechanisms where the voltage at the input terminal is tracked and used to control the current sources. The op-amp or control circuit monitors the voltage and adjusts the compensation current accordingly, creating a closed-loop system that automatically maintains the desired capacitance behavior without requiring complex manual adjustment circuits
3Quantity of substance
If traditional capacitor circuits are used, then the capacitance is improved, but the adjustability to desired capacitance values is difficult
Solution Approach 1:
The patent implements dynamic adjustability through controlled current sources that can be programmed or tuned to provide different compensation current levels. The capacitance value is determined by the ratio of currents and the core capacitance, allowing continuous or discrete adjustment by changing control parameters rather than physically replacing components, thus enabling easy adaptation to different desired capacitance values
4Quantity of substance
If capacitor circuits are designed to provide increased capacitance, then the capacitance is improved, but the power consumption is increased
Solution Approach 1:
The patent utilizes periodic switching action of the transistors and current sources to achieve the capacitance multiplication effect. By switching the current sources in a controlled periodic manner synchronized with the signal frequency, the system achieves high effective capacitance with low average power consumption, as the current sources are active only during specific phases of the cycle rather than continuously
Data Source
AI summary
The present disclosure provides a capacitance circuit which has an input terminal and is configured to provide an increased capacitance between the input terminal and a first reference voltage. The capacitance circuit comprises a current source structure configured to provide a compensation current at the input terminal, a first transistor having a first control terminal and a first load current and being coupled to the input terminal, a second transistor having a second control terminal, a capacitance amplification circuit configured to provide a capacitance amplification factor and being coupled between the first control terminal and the second control terminal, and a capacitor having a core capacitance and being coupled between the first control terminal and the input terminal, wherein the compensation current corresponds to the first load current during direct current operation, and wherein the increased capacitance is based on the core capacitance and the capacitance amplification factor.