Switched Capacitor Circuit for Die-Area Efficient Capacitance Scaling
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Solution Overview
Problem
Integrated circuit (IC) capacitors are limited in size due to space constraints, leading to the need for either large capacitors that occupy too much space or discrete components that increase cost and complexity, while performance requirements often necessitate minimal size and higher capacitance.
Innovation Solution
The development of a super scale switched capacitor circuit that uses current duplication circuits and operational amplifiers to effectively increase or decrease the capacitance of a capacitor, allowing a small capacitor to function like a larger one or a large capacitor to act like a smaller one through capacitance multipliers and dividers, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the capacitance of an IC capacitor is increased to meet performance requirements, then the capacitance value is improved, but the area occupied on the semiconductor die increases
Solution Approach 1:
The patent employs current mirrors to create copies of the capacitor's current, effectively multiplying the capacitor's function. By sensing the current through the capacitor and generating multiple copies through current mirror circuits, the system achieves an effective capacitance that is a multiple of the physical capacitor's capacitance, allowing a small physical capacitor to function as a larger capacitor
Solution Approach 2:
The patent changes the effective capacitance parameter through circuit multiplication rather than physically changing the capacitor's size. By using current duplication circuits with multiplication factors, the effective capacitance can be dynamically adjusted and scaled without changing the physical dimensions of the capacitor or its occupation on the semiconductor die
2Quantity of substance
If discrete capacitors are used to achieve higher capacitance values, then the capacitance requirement is met, but the system complexity and cost increase
Solution Approach 1:
The patent merges the capacitor function with current mirror circuits to create an integrated capacitance multiplication system. Instead of using separate discrete capacitors, the system combines the physical capacitor with current sensing and duplication circuits to achieve the desired effective capacitance within a single integrated circuit block, reducing overall system complexity
Solution Approach 2:
The current mirror circuits serve multiple functions: they sense the capacitor current, multiply the current signal, and feed it back to achieve capacitance multiplication. This multi-functional approach eliminates the need for separate discrete components while achieving the same effect, thereby reducing system complexity and integration requirements
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 solution enables the realization of effective capacitance values beyond the physical limitations of IC capacitors, allowing for more efficient use of space and reducing system complexity and cost by mimicking larger or smaller capacitance values without the need for discrete components.
Implementation Method 1
When a voltage is applied to the capacitor, an electric field develops across the dielectric, causing a net positive charge to collect on one plate (i.e., the positive plate) and net negative charge to collect on the other plate (i.e., the negative plate).
Implementation Method 2
The effect of a capacitor is known as capacitance. Capacitance can be defined as C=Q/V, or the ratio of the electric charge Q on each plate to the potential difference V between them.
Implementation Method 3
A current mirror circuit 202 is coupled to the capacitor and is configured to output the charge current as a function of the charge current flowing through the capacitor.
Implementation Method 4
A capacitance multiplier is a circuit that is designed to make a small capacitor function like a capacitor that is much larger.
Data Source
AI summary
A super scale switched capacitor for an integrated circuit is disclosed. In one embodiment the super scale switched capacitor circuit includes a capacitor coupled between a first node and a second node. A circuit is also included that contains a first circuit and a second circuit. The first circuit is configured to output a first current, which is a multiple of current effectively flowing through the capacitor from the second node to the first node. The second circuit is configured to input a second current, which is a multiple of current effectively flowing through the capacitor from the first node to the second node.