On-Chip Temperature Detection Using Oscillator Frequency Analysis

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Solution Overview

Problem

Current methods lack efficient and precise means to verify the process corner and operating temperature of integrated circuits, which are crucial for optimizing circuit performance and design variations, especially in high-speed circuits where power consumption and space are concerns.

Innovation Solution

An on-chip detection circuit utilizing low-power CMOS oscillators, a voltage regulator, and counters to determine the free running frequency of P and N oscillators, combined with look-up tables to correlate frequency data with process corners and temperature, allowing for accurate classification and model verification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If verification circuits are added to determine process corner and temperature, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improveprocess corner and temperature verification accuracyVSAvoidcircuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The oscillator circuit serves multiple functions: it acts as both a functional circuit element and a temperature sensor, while also providing process corner information. By making the oscillator multi-functional, the patent avoids adding separate dedicated verification circuits, thus improving measurement precision without significantly increasing device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The oscillator automatically provides temperature and process information through its inherent frequency characteristics without requiring external measurement equipment. The circuit serves itself by using its own operational parameters (frequency) to convey diagnostic information about process corner and temperature conditions

Inventive Principle:

Principle #25Self-service

2Measurement precision

If verification circuits are added to determine process corner and temperature, then measurement precision is improved, but power consumption increases

Engineering Contradiction:

Improveprocess corner and temperature verification accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The oscillator performs multiple roles including signal generation and temperature sensing, eliminating the need for separate power-hungry measurement circuits. This multi-functionality approach maintains measurement precision while minimizing additional power consumption

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces physical thermal sensing mechanisms with electronic frequency measurement. By substituting mechanical/thermal measurement systems with electronic oscillation frequency analysis, the solution achieves accurate temperature measurement with lower power consumption

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If verification circuits are added to determine process corner and temperature, then measurement precision is improved, but area of chip increases

Engineering Contradiction:

Improveprocess corner and temperature verification accuracyVSAvoidchip area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The oscillator circuit is designed to serve multiple purposes within the same physical footprint, providing both functional operation and diagnostic information. This eliminates the need for separate dedicated verification circuit blocks, maintaining measurement precision while minimizing chip area increase

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the verification functionality with existing oscillator circuits rather than adding separate measurement systems. By merging temperature sensing and process verification functions into the oscillator design, the solution achieves accurate measurements without significant area overhead

Inventive Principle:

Principle #5Merging (Combining)

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

Enables precise determination of process corners and operating temperatures, enhancing circuit performance, verifying simulation models, and optimizing power consumption and chip space usage without significant power or area overhead.

Implementation Method 1

a temperature sensitive oscillator which may be a PN oscillator whose speed varies with temperature

Methodology Applied

Scientific EffectTemperature-dependent frequency oscillation:

Data Source

PatentUS8801281B1On-chip temperature detection using an oscillator

Publication Date: 2014.08.12 PIXELWORKS SEMICON TECH SHANGHAI CO LTD

AI summary

A temperature detection circuit on an integrated circuit has a temperature sensitive oscillator, at least one temperature insensitive oscillator, a reference clock, process detection circuitry coupled to an output of the temperature insensitive oscillator and the output of the reference clock, the process detection circuitry to compare the outputs and produce a process signal, and temperature reference circuitry coupled to an output of the temperature sensitive oscillator, the output of the reference clock, and the process signal, the temperature detection circuitry to produce a temperature for the integrated circuit.