Current-Mirror Capacitor Amplification Without Op-Amp Compensation

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Solution Overview

Problem

Conventional capacitor amplifying circuits require operational amplifiers to achieve capacitance compensation, increasing complexity and cost, and making it difficult to reduce the size of integrated circuits.

Innovation Solution

A capacitor amplifying circuit using a current mirror unit with multiple stages of current mirror circuits in series, coupled between two current sources and an output capacitor, to achieve equivalent capacitance magnification without the need for an operational amplifier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an operational amplifier is added to achieve capacitance compensation, then the frequency response is compensated and capacitance amplification is achieved, but the circuit complexity increases and manufacturing cost increases

Engineering Contradiction:

Improvefrequency response compensationVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the operational amplifier from the traditional capacitor amplifying circuit, replacing it with a current mirror circuit configuration. This extraction eliminates the need for the operational amplifier while maintaining the capacitance amplification function through the current mirror's proportional current relationships

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes the operational amplifier (an active amplifying device) with a passive current mirror circuit that uses current proportional relationships to achieve the same functional effect. The current mirror circuit replaces the mechanical/electronic amplification mechanism with a current-based proportional relationship mechanism

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If an operational amplifier is added to achieve capacitance amplification, then the capacitance compensation effect is achieved, but the manufacturing cost increases

Engineering Contradiction:

Improvecapacitance compensation effectVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the expensive operational amplifier with a more cost-effective current mirror circuit implementation. The current mirror circuit uses simpler components (current sources and mirror transistors) that are cheaper to manufacture and integrate, thereby reducing the overall manufacturing cost while maintaining the capacitance compensation effect

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If an operational amplifier is added to the circuit, then the capacitance amplification function is achieved, but the circuit size increases

Engineering Contradiction:

Improvecapacitance amplification functionVSAvoidcircuit area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent extracts the operational amplifier from the circuit and replaces it with a compact current mirror circuit. This extraction removes the large-area operational amplifier component while maintaining the essential capacitance amplification function through the current mirror's proportional current relationships, thereby reducing the overall circuit area

Inventive Principle:

Principle #2Taking out (Extraction)

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 allows for the amplification of smaller capacitance values to equivalent larger values, reducing manufacturing costs, simplifying the circuit structure, and shrinking the size of the capacitor amplifying circuit, thereby enhancing its market competitiveness.

Implementation Method 1

The current mirror unit is coupled between the first current source and the second current source. The current mirror unit includes N stages of current mirror circuit in series, wherein N is larger than or equal to 1. Each of the N stages of current mirror circuit has a proportional constant respectively.

Methodology Applied

Scientific EffectCurrent mirror effect:

Data Source

PatentUS8816760B2Capacitor amplifying circuit and operating method thereof

Publication Date: 2014.08.26 UPI SEMICON CORP

AI summary

A capacitor amplifying circuit and an operating method thereof are disclosed. The capacitor amplifying circuit includes a first current source, a second current source, a current mirror unit, and an output capacitor. There is a proportion relationship between a first current of the first current source and a second current of the second current source. The current mirror unit is coupled between the first current source and the second current source. The current mirror unit includes N stages of current mirror circuit in series, wherein N is larger than or equal to 1. Each of the N stages of current mirror circuit has a proportional constant respectively. Two terminals of the output capacitor are coupled to the current mirror unit and a ground terminal respectively. The equivalent capacitance magnification of the output capacitor is related to the proportional constants based on the proportion relationship.