Integrated Circuit Temperature Control Using Switched Current Sources

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Solution Overview

Problem

Existing on-chip temperature measurement methods for integrated circuits are inaccurate due to PVT dependency, leakage issues, and amplifier offset errors, which can lead to thermal run-away and chip damage during high core activity.

Innovation Solution

A method using multiple diodes placed in local areas of the chip, with a mid-range voltage logic and error correction techniques to generate accurate temperature data, involving switched current sources and a differential amplifier to calculate an error-corrected difference between voltage outputs, reducing amplifier offset and quantization errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple diodes are placed in different local areas of the chip for temperature monitoring, then temperature measurement coverage is improved, but chip routing resources are consumed and diode mismatch errors occur

Engineering Contradiction:

Improvetemperature measurement accuracyVSAvoidrouting complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the temperature sensing function from multiple distributed diodes and consolidates it into a single diode by using temporal sampling at different current levels. Instead of spatially distributing multiple sensors, the solution uses a single sensor with varied excitation conditions to achieve the same monitoring capability, thereby eliminating routing complexity while maintaining measurement precision.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the excitation current parameter of a single diode to achieve temperature measurement. By measuring the diode voltage at multiple different current levels (first, second, and third current levels) and using the relationships between these measurements, the system can calculate temperature without requiring multiple physical diodes, thus avoiding routing complexity and diode mismatch errors.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If a sample-and-hold architecture with switches and capacitors is used to reduce diode mismatch errors, then routing complexity is reduced, but leakage currents degrade measurement accuracy

Engineering Contradiction:

Improverouting complexityVSAvoidtemperature measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent converts the harmful leakage currents into useful measurement information. By deliberately applying multiple different current levels to the diode and measuring the voltage responses, the system can distinguish between leakage effects and actual temperature signals. The mathematical relationships between measurements at different current levels allow the system to extract accurate temperature data while accounting for leakage currents, thereby converting this previously harmful effect into a beneficial measurement mechanism.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If external thermo-sensors are used to monitor chip temperature, then temperature monitoring capability is provided, but cost increases and response speed decreases due to package thermal capacitance

Engineering Contradiction:

Improvetemperature monitoring capabilityVSAvoidtemperature response speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent makes the integrated circuit itself serve as the temperature sensor by utilizing the existing diode structure within the chip. The diode's forward voltage characteristic inherently provides temperature information, eliminating the need for separate external temperature sensors. This self-service approach enables the chip to monitor its own temperature internally, providing both the reliability of dedicated temperature monitoring and the speed advantage of direct chip-level measurement without package thermal capacitance delays.

Inventive Principle:

Principle #25Self-service

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 approach provides accurate temperature monitoring at the local block level, preventing thermal-induced damage by enabling timely responses to temperature increases without the need for complex routing or external components, improving accuracy and reducing errors.

Implementation Method 1

generating a first, second and third voltage output from a temperature sensing element of an integrated circuit using a respective, corresponding first, second and third, switched current source

Methodology Applied

Scientific EffectTemperature-dependent voltage characteristics of semiconductor junctions:

Data Source

PatentUS8290728B2Method and apparatus for integrated circuit temperature control

Publication Date: 2012.10.16 ATI TECHNOLOGIES ULC

AI summary

A method includes generating a first, second and third voltage output from a temperature sensing element of an integrated circuit using a respective, corresponding first, second and third, switched current source, for sequentially switching a respective first, second and third excitation current through the temperature sensing element. The third switched current source generates the corresponding third voltage output as a reference voltage between the first voltage and the second voltage. An error corrected difference is calculated between the first voltage and the second voltage using the reference voltage. In the method, the second excitation current is proportional to the first excitation current by a value n, and the third excitation current is proportional to the first excitation current by the square root of n.