Temperature-to-digital converter

Abstract

A temperature to digital converter device is implemented by integrating a temperature sensor circuit into an analog-to-digital converter (ADC). Temperature-to-digital conversion is accomplished by first measuring a change in voltage (ΔVBE) across the junction of a diode when different current densities are forced through the junction. The thus obtained ΔVBE is proportional to temperature. As part of the conversion processing, ΔVBE is multiplied by a fixed gain, and an offset voltage value is subtracted from ΔVBE. The multiplication and subtraction functions are performed by a switched-capacitor integrator in a delta-sigma ADC and the ADC itself operates as the temperature-to-digital converter device, eliminating the extra amplifier and / or capacitors required when the multiplication and / or subtraction function are performed outside the ADC. Alternately, other ADC topologies that include an integrator or gain amplifier, such as pipeline ADCs and cyclic ADCs may be used in place of the delta-sigma ADC.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to the field of integrated circuit design and, more particularly, to the design of temperature measuring devices and analog-to-digital converters in integrated circuit systems. 2. Description of the Related Art Many digital systems, especially those that include high-performance, high-speed circuits, are prone to operational variances due to temperature effects. Devices that monitor temperature and voltage are often included as part of such systems in order to maintain the integrity of the system components. Personal computers (PC), signal processors and high-speed graphics adapters, among others, typically benefit from such temperature monitoring circuits. For example, a central processor unit (CPU) that typically “runs hot” as its operating temperature reaches high levels may require a temperature sensor in the PC to insure that it doesn't malfunction or break due to thermal problems. Often...

AI Technical Summary

Benefits of technology

This approach enables accurate and efficient temperature-to-digital conversion with a reduced component count, improving the dynamic range matching and centering of the ΔVBE signal to the ADC's dynamic range, thus enhancing the precision and area efficiency of temperature monitoring.

Problems solved by technology

Many digital systems, especially those that include high-performance, high-speed circuits, are prone to operational variances due to temperature effects.

Temperature-to-digital converters (TDC) of such implementations usually contain complex circuits with high power dissipation.

The yield of these TDCs during the fabrication process may also be low as there are many components that need to be matched for a given process spread.

Disadvantages of the typical system as illustrated in FIG. 1 include a need for large capacitors (such as CI and CT) to meet matching requirements for a fixed-gain amplifier.

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