US 9,429,605 B2 · Techniques for determining a resistance value

Abstract

Some embodiments relate to an integrated circuit (IC). The IC determines a time-variant resistance of an sensing resistor, wherein a resistance of the sensing resistor reflects an ambient environmental condition. The IC includes first and second conditioning circuits, an analog to digital conversion (ADC) element, and a logic circuit. The first conditioning circuit provides a first voltage based on the resistance of the sensing resistor, while the second conditioning circuit provides a second voltage based on a resistance of an on-chip reference resistor. The ADC element provides a multi-bit digital value based on a ratio of the first and second voltages. The multi-bit digital value is indicative of the ambient environmental condition measured by the off-chip sensor. A logic circuit selectively adjusts the first and second voltages based on the multi-bit digital value to limit or avoid saturation of the ADC element. Other embodiments are also disclosed.

Claims23

Dependent claims

An integrated circuit (IC) for determining a time-variant resistance of a sensing resistor, wherein a resistance of the sensing resistor at a given time reflects an ambient environmental condition near the sensing resistor at that time, the IC comprising:

a first conditioning circuit to provide a first voltage based on the resistance of the sensing resistor, the sensing resistor having a negative temperature coefficient;
a second conditioning circuit to provide a second voltage based on a resistance of an on-chip reference resistor;
an analog to digital conversion (ADC) element configured to concurrently receive the first and second voltages and provide a multi-bit digital value based on a ratio of the first and second voltages, the multi-bit digital value indicative of the ambient environmental condition measured by the sensing resistor;
and
a logic circuit to selectively adjust the first and second voltages based on the multi-bit digital value to limit or avoid saturation of the ADC element.

2 more elements

An apparatus, comprising:

a sensing resistor having a time-varying resistance exhibiting a negative temperature coefficient, wherein a resistance of the sensing resistor at a given time reflects an ambient environmental condition near the sensing resistor at that time;
a first conditioning circuit to provide a first current to the sensing resistor and to output a first voltage based on the resistance of the sensing resistor;
a second conditioning circuit to provide a second current to a reference resistor and to output a second voltage which has a substantially fixed voltage level, the reference resistor being matched to the sensing resistor;
an analog to digital conversion (ADC) element configured to concurrently receive the first and second voltages and provide a multi-bit digital value based on a ratio of the first and second voltages, the multi-bit digital value indicative of the resistance of the sensing resistor and a corresponding ambient environmental condition;
and
a logic circuit arranged on a feedback path between an output of the ADC element and respective inputs of the first and second conditioning circuits and adapted to selectively adjust the first and second currents as well as the first and second voltages based on the multi-bit digital value.

3 more elements

Dependencies are inferred from the claim text.

Techniques for determining a resistance value

Life of this patent

Techniques for determining a resistance value

Life of this patent

Abstract

Claims23