Reference Circuit Topology for Low-Power Stable Voltage and Current

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Solution Overview

Problem

Existing reference circuits for providing voltage and current references consume relatively high power and are sensitive to parameter variations such as temperature and supply voltage.

Innovation Solution

A compact reference circuit design that incorporates an operational amplifier with a current mirror, allowing the same drain current to flow through two transistors, which generates both the voltage and current references, thereby eliminating the need for a separate voltage reference circuit. This design utilizes pMOS transistors for stability and includes a reference resistor and transistor to provide the current reference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a voltage reference circuit is combined with an operational amplifier to implement a current reference circuit, then the reference voltage and current can be provided, but the power consumption becomes relatively large

Engineering Contradiction:

Improvereference voltage stabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent combines the voltage reference circuit and current reference circuit into a single integrated structure. The operational amplifier's input transistors (first and second transistors) are configured to generate the reference voltage, while the same transistors plus a current mirror generate the reference current. This merging eliminates the need for separate independent circuits, reducing overall power consumption while maintaining both reference functions.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The first and second transistors serve multiple functions: they act as input transistors for the operational amplifier, generate the reference voltage at their drain connection point, and simultaneously serve as part of the current reference generation path through the current mirror. This multi-functionality reduces the total number of active components and lowers power consumption.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a separate voltage reference circuit is used to provide reference voltage to the operational amplifier, then the reference voltage can be generated, but the circuit area increases

Engineering Contradiction:

Improvereference voltage generationVSAvoidcircuit area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The voltage reference generation function is merged into the operational amplifier's input stage. The connection point between the drain of the first transistor and the drain of the second transistor serves as the reference voltage output, eliminating the need for a separate voltage reference circuit block and reducing overall circuit area.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The input transistors of the operational amplifier are designed to simultaneously generate the reference voltage, making the operational amplifier serve dual purposes: signal amplification and reference voltage generation. This eliminates redundant circuitry and reduces the total area occupied by the reference circuit.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If conventional reference circuits are used, then reference voltage and current can be provided, but the circuits become sensitive to temperature and supply voltage variations

Engineering Contradiction:

Improvereference stabilityVSAvoidparameter variations sensitivity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The operational amplifier provides negative feedback by comparing the reference voltage (generated by the first and second transistors) with the voltage at its inverting input. This feedback mechanism actively compensates for variations due to temperature and supply voltage changes, maintaining stable reference voltage and current outputs despite environmental variations.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The circuit uses the inherent temperature-dependent characteristics of the transistors (such as threshold voltage and mobility variations) in a controlled manner. By operating the transistors in specific regions and using the operational amplifier's feedback to compensate, the circuit transforms potential sources of instability into stable reference outputs that are insensitive to temperature and supply voltage variations.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12306649B2Reference circuit and a power management unit

Publication Date: 2025.05.20 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)

AI summary

A reference circuit for providing voltage reference and current reference comprises: operational amplifier comprising first transistor, second transistor and current mirror being configured to force a same drain current through first and second transistor, wherein first and second transistor control voltage reference at first node of reference circuit; and reference output comprising reference resistor connected between ground and first node and reference transistor, whereby reference circuit is configured to provide voltage reference at first node and current reference through reference resistor and reference transistor.