Low Power Current Source with Auxiliary Mirror

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Solution Overview

Problem

Current current sources for electronic systems face challenges in providing a constant current that is independent of transistor current gain, while also needing to consume less power, occupy less area, and remain stable against temperature and environmental fluctuations.

Innovation Solution

The implementation of a current source with an auxiliary current mirror that reduces the size of the characteristic resistor, using interconnected transistors in multiple circuits to generate and maintain a constant current, and employing semiconductor technologies like CMOS and BJT to achieve low current levels without increasing the resistor size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the size of the characteristic resistor is increased to produce low current levels, then the current consumption is reduced, but the on-chip area occupancy increases

Engineering Contradiction:

Improvecurrent consumptionVSAvoidon-chip area occupancy

Core Design Contradiction:

Use of energy by moving objectVSArea of stationary object

Solution Approach 1:

The current source is divided into multiple circuits: a first circuit that generates a reference current, a second circuit that generates an output current identical to the reference current, and a third circuit that drives a multiple of the reference current into the characteristic resistor. This segmentation allows the use of a smaller resistor while maintaining low current consumption through current multiplication.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the operating parameters by using a multiple of the reference current (driven by the third circuit) to flow through the characteristic resistor. This allows the resistor to be smaller while still achieving the desired low current levels at the output, effectively decoupling the resistor size from the current consumption requirement.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If the size of the characteristic resistor is increased to produce low current levels, then the current consumption is reduced, but the on-chip area occupancy increases

Engineering Contradiction:

Improvecurrent consumptionVSAvoidcircuit complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The first circuit serves multiple functions: it generates the reference current that is used by both the second circuit (to produce the output current) and the third circuit (to drive the multiple current into the resistor). This multi-functionality reduces overall device complexity by sharing the reference current generation function across multiple operational paths.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The second circuit creates a copy of the reference current as the output current, ensuring that the output is identical to the reference current. This copying mechanism simplifies the design by using the same reference current generation logic for both direct reference and output generation.

Inventive Principle:

Principle #26Copying

3Use of energy by moving object

If a larger resistor is used to reduce current levels, then power consumption is reduced, but the stability against temperature fluctuations deteriorates

Engineering Contradiction:

Improvepower consumptionVSAvoidcurrent constancy

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The invention changes the current parameter through the third circuit, which drives a multiple of the reference current into the characteristic resistor. This allows the use of a smaller resistor with better temperature stability characteristics while maintaining the desired low power consumption through the current multiplication approach.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8729883B2Current source with low power consumption and reduced on-chip area occupancy

Publication Date: 2014.05.20 SYNOPSYS INC

AI summary

A current source with low power consumption and reduced on-chip area occupancy. The current source for providing a constant current to a load includes a first circuit that generates a reference current. The first circuit includes a first plurality of interconnected transistors. The current source also includes a characteristic resistor, coupled to the first circuit, that determines value of the reference current. The current source further includes a second circuit and a third circuit. The second circuit, coupled to the first circuit and to the load, generates an output current that is identical to the reference current. The second circuit includes a second plurality of interconnected transistors. The third circuit, coupled to the first circuit, drives a multiple of the reference current into the characteristic resistor. The third circuit includes a third plurality of interconnected transistors.