AN 769: Intel FPGA Remote Temperature Sensing Diode Implementation Guide

Download PDF
ID 683139
Date 4/06/2022
Public
Document Table of Contents
Document Table of Contents x
1. Introduction 2. Implementation Overview 3. Implementation Consideration 4. Evaluation Results 5. Conclusion 6. Document Revision History for AN 769: Intel FPGA Remote Temperature Sensing Diode Implementation Guide
3. Implementation Consideration x
3.1. Ideality Factor (η-Factor) Mismatch 3.2. Series Resistance Error 3.3. Temperature Diode Beta Variation 3.4. Differential Input Capacitor 3.5. Offset Compensation
4. Evaluation Results x
4.1. Evaluation with Maxim Integrated* 's MAX31730 Temperature Sensing Chip Evaluation Board 4.2. Evaluation with Texas Instruments* 's TMP468 Temperature Sensing Chip Evaluation Board
1. Introduction
2. Implementation Overview
3. Implementation Consideration
4. Evaluation Results
5. Conclusion
6. Document Revision History for AN 769: Intel FPGA Remote Temperature Sensing Diode Implementation Guide

3.3. Temperature Diode Beta Variation

As process technology geometries gets smaller, the Beta(β) value of the PNP or NPN substrate decreases.

As the temperature diode Beta value gets lower, especially if the temperature diode collector is tied to the ground, the Beta value affects the current ratio on . Therefore, maintaining an accurate current ratio is crucial.

Some temperature sensing chips have built-in Beta compensation feature. The Beta variation of the circuitry senses the base current and adjusts the emitter current to compensate for the variation. The Beta compensation maintains the collector current ratio.

Figure 4.  Intel® Stratix® 10 Core Fabric Temperature Diode with Maxim Integrated* 's MAX31730 Beta Compensation EnabledThis figure shows that the measurement accuracy is achieved with Beta compensation enabled. The measurements were taken during FPGA power down condition—the set and measured temperatures are expected to be close.


Level Two Title