Method and apparatus for precision temperature sensing
AssigneeAvago Technologies International Sales Pte. Limited
InventorsKareem Abdelghani Ibraheem Mohamed Ragab, Xiaofeng Lin, Darwin Cheung, Chi Mo, Vinay Chandrasekhar, Jungwoo Song, Xicheng Jiang
Life of this patent
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Abstract
An apparatus includes a switched-capacitor resistor that provides an equivalent resistance that can be used as a reference resistor. The switched-capacitor resistor includes a capacitor and a pair of switches that alternately switch (e.g., open and close) in order to charge and discharge the capacitor. The switching frequency of the switches can be controlled by a clock phase generator that generates non-overlapping pulses. To further control the frequency, a frequency locked loop circuit can also be used.
Claims18
An apparatus, comprising:
- a first resistor comprising a resistance configured to change based on a temperature change of the first resistor;
- a first switch controlled by a first pulse;
- a second switch controlled by a second pulse;
- and
- a capacitor, wherein:
- in response to the first switch closing, the second switch is configured to open and the capacitor is configured to charge,
- in response to the second switch closing, the first switch is configured to open and the capacitor is configured to discharge, and
- in response to the capacitor charging and discharging, the capacitor is configured to provide a reference resistor for the apparatus;
- and
- wherein the first pulse is non-overlapping with the second pulse such that only one of the first switch or the second switch is closed at a given time.
A temperature sensing circuit, comprising:
- a resistor configured to provide a first resistance;
- a first switch;
- a second switch, wherein the first switch and the second switch are configured to alternately open and close based on a switching frequency;
- a capacitor;
- and
- a generator circuit configured to generate clock signals that are at least partially non-overlapping, each of the clock signals having a duty cycle such that only one of the first switch and the second switch is closed at a given time, wherein:
- the switching frequency of the first switch and the second switch is based on the clock signals, and
- the capacitor is configured to provide a second resistance based on the switching frequency.
A temperature sensing circuit, comprising:
- a voltage source;
- a resistor coupled to the voltage source, the resistor configured to provide a first resistance based on a temperature at the resistor;
- a capacitor configured to provide a second resistance based on a switching frequency of switches that control charging and discharging of the capacitor;
- a generator circuit configured to provide first and second clock signals that are non-overlapping such that only one of the switches is closed at a given time, whereby the capacitor alternately charges and discharges to provide the second resistance;
- and
- an analog-to-digital converter (ADC) configured to convert an analog signal from the resistor to a generate a digital output, wherein the digital output corresponds to the temperature.
Dependencies are inferred from the claim text.