Current Reference Circuit Using PTAT and Band-Gap Merging

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Solution Overview

Problem

Conventional current reference circuits are significantly influenced by temperature and voltage changes, leading to increased size and power consumption due to the need for additional circuitry to mitigate these dependencies.

Innovation Solution

A current reference circuit incorporating a proportional-to-absolute temperature (PTAT) current generator, a band-gap reference circuit, and a current replication circuit, which generates currents with zero and positive temperature coefficients, respectively, to replicate and stabilize the current output, thereby reducing temperature and voltage dependencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional circuitry is added to reduce temperature and voltage dependency, then temperature stability and voltage stability are improved, but circuit size and power consumption increase

Engineering Contradiction:

Improvetemperature stabilityVSAvoidcircuit size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines the PTAT current generator and band-gap reference circuit into a unified current reference circuit that generates multiple currents with different temperature coefficients (zero temperature coefficient current and positive temperature coefficient current) from a single PTAT current source, achieving temperature compensation without requiring separate independent circuits for each function

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The PTAT current generator serves multiple functions: it generates the PTAT current directly, enables generation of zero temperature coefficient current through band-gap reference circuit, and enables generation of positive temperature coefficient current, reducing the need for separate dedicated circuits for each current type

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If additional circuitry is added to reduce temperature and voltage dependency, then voltage stability is improved, but power consumption increases

Engineering Contradiction:

Improvevoltage stabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The circuit uses the PTAT current to self-regulate and compensate for temperature and voltage variations through the band-gap reference mechanism, reducing the need for external adjustment circuits and minimizing additional power consumption

Inventive Principle:

Principle #25Self-service

3Area of stationary object

If conventional current reference circuit is used, then circuit size is minimized, but temperature dependency and voltage dependency increase

Engineering Contradiction:

Improvecircuit sizeVSAvoidtemperature dependency

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent changes the temperature coefficient parameters by generating multiple currents with different temperature characteristics (zero temperature coefficient and positive temperature coefficient) from the same PTAT current source, allowing the circuit to compensate for temperature variations while maintaining a compact structure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The circuit combines currents with different temperature coefficients (zero temperature coefficient current and positive temperature coefficient current) to create a composite current reference that compensates for temperature effects, analogous to using composite materials to achieve desired properties

Inventive Principle:

Principle #40Composite materials

4Area of stationary object

If conventional current reference circuit is used, then circuit size is minimized, but voltage dependency increases

Engineering Contradiction:

Improvecircuit sizeVSAvoidvoltage dependency

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8358119B2Current reference circuit utilizing a current replication circuit

Publication Date: 2013.01.22 SAMSUNG ELECTRONICS CO LTD

AI summary

A current reference circuit includes a proportional-to-absolute temperature (PTAT) current generator, a band-gap reference circuit and a current replication circuit. The PTAT generator generates a PTAT current. The band-gap reference circuit generates a reference voltage based on the PTAT current and generates a second current by cancelling a first current from the PTAT current. The first current has a zero temperature coefficient and the second current has a positive temperature coefficient. The current replication circuit replicates the first current based on the PTAT current and the second current.