On-Die Thermal Sensor ADC with Dual Tracking for Fast Accuracy

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Solution Overview

Problem

Conventional on-die thermal sensors (ODTS) in semiconductor memory devices face inefficiencies in analog-to-digital conversion, particularly in tracking operations, leading to prolonged conversion times and unreliable accuracy, especially when temperature voltages change during the initial tracking period.

Innovation Solution

Implementing a dual-tracking scheme for the analog-to-digital converter (ADC) within the ODTS, where a successive approximation register (SAR) scheme is used during the initial tracking period for fast digital code determination and a sequential access scheme is employed after the initial period to maintain accurate conversions with smaller unit variations, allowing for rapid adaptation to changes in temperature voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional tracking ADC uses a single tracking scheme with fixed unit variation width, then the circuit structure remains simple, but the conversion time is prolonged and accuracy deteriorates when temperature voltage changes during initial tracking

Engineering Contradiction:

Improvetemperature measurement accuracyVSAvoidconversion time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the ADC's tracking scheme changeable over time. It transitions from a first tracking scheme with large unit variation width (for fast initial conversion) to a second tracking scheme with small unit variation width (for high-precision final conversion). This dynamic adaptation allows the system to optimize both speed and accuracy at different stages of the conversion process, resolving the contradiction between conversion time and measurement precision.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent uses preliminary action by performing a rough conversion first using the first tracking scheme with large unit variation width. This preliminary conversion quickly brings the tracking voltage close to the input voltage, establishing a good initial condition. Then the second tracking scheme with small unit variation width performs the final precise conversion. This two-stage approach pre-pares the system for high-precision measurement, reducing the time needed for accurate conversion.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the ADC uses large unit variation width for fast conversion, then conversion speed improves, but measurement accuracy deteriorates

Engineering Contradiction:

Improveconversion speedVSAvoiddigital code accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent segments the conversion process into two distinct stages: initial conversion using the first tracking scheme with large unit variation width for speed, and final conversion using the second tracking scheme with small unit variation width for precision. This segmentation allows each stage to optimize for its specific goal, resolving the contradiction between conversion speed and measurement accuracy by applying different tracking characteristics to different phases of the same conversion task.

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If the ADC uses small unit variation width for accurate conversion, then measurement precision improves, but conversion time increases

Engineering Contradiction:

Improvedigital code accuracyVSAvoidconversion speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

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 enables high-speed analog-to-digital conversion, ensuring accurate and rapid output of digital temperature signals even when input analog signals change, thereby improving power efficiency and reducing data loss in semiconductor memory devices.

Implementation Method 1

the ODTS measures the internal temperature of the semiconductor device using the fact that the change in a base-emitter voltage (VBE) of a bipolar junction transistor (BJT) is about −1.8 mV/° C.

Methodology Applied

Scientific EffectBase-emitter voltage temperature dependence:

Data Source

PatentUS7508332B2On die thermal sensor having analog-to-digital converter for use in semiconductor memory device

Publication Date: 2009.03.24 SK HYNIX INC

AI summary

An On Die Thermal Sensor (ODTS) of a semiconductor memory device includes: a temperature detector for detecting an internal temperature of the semiconductor memory device to generate a temperature voltage corresponding to the detected internal temperature; a tracking ADC for outputting a digital code by comparing the temperature voltage with a tracking voltage and performing a counting operation to the result of comparison; and an operation controller for controlling operations of the temperature detector and the analog-to-digital converter, wherein the tracking ADC performs the counting operation using a first tracking scheme having a relatively large unit variation width of the digital code value during an initial tracking period and a second tracking scheme having a relatively small unit variation width of the digital code value after the initial tracking period.