Highly accurate temperature sensors, and calibrations thereof, for use with implantable medical devices

Patent metadata

Field	Value
Publication number	US-11077308-B2
Application number	US-201816171103-A
Country	US
Kind code	B2
Filing date	Oct 25, 2018
Priority date	Oct 25, 2018
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

Certain embodiments of the present technology relate to temperature sensors for using in an implantable medical device, and methods for use therewith. Such a method can include alternating between producing a first base-to-emitter voltage drop (VBE1) and a second base-to-emitter voltage drop (VBE2), and alternating between using a capacitor to store the VBE1, which is complimentary to absolute temperature (CTAT), and using the same capacitor to store a ΔVBE=VBE2−VBE1, which is proportion to absolute temperature (PTAT). The method also includes using a sigma-delta modulator that includes the capacitor to produce a signal having a duty cycle (dc) indicative of the ΔVBE stored using the capacitor, and producing a temperature measurement based on the signal having the duty cycle (dc) indicative of the ΔVBE.

First claim

What is claimed is:

1. A method for producing a temperature measurement for use in an implantable medical device (IMD), the method comprising:
alternating between providing a first amount of current to a diode device and a second amount of current to the same diode device to thereby alternate between producing a first base-to-emitter voltage drop (VBE1) and a second base-to-emitter voltage drop (VBE2) using the same diode device;
alternating between using a capacitor to store the VBE1, which is complimentary to absolute temperature (CTAT), and using the same capacitor to store a ΔVBE=VBE2−VBE1, which is proportion to absolute temperature (PTAT);
producing, using a sigma-delta modulator that includes the same capacitor used to store the VBE1 and the ΔVBE, a signal having a duty cycle (dc) indicative of the ΔVBE; and
producing a temperature measurement based on the signal having the duty cycle (dc) indicative of the ΔVBE;
wherein the sigma-delta modulator includes a summing node, an integrator, a 1-bit quantizer, and a 1-bit digital-to-analog converter (DAC), the integrator including an operational amplifier (op-amp) having first and second inputs and an output, with one of the first and second inputs coupled to the summing node, and the integrator also including a switch between the output of the op-amp and an input of the 1-bit quantizer;
wherein the same capacitor that is used to store both the VBE1 and the ΔVBE is part of both the integrator and the 1-bit DAC of the sigma-delta modulator; and
wherein the method includes controlling the switch to selectively couple the output of the op-amp to the input of the 1-bit quantizer.

2. The method of claim 1 , wherein:
the summing node is coupled to a terminal of the diode device that alternately produces the VBE1 and the VBE2;
the signal having the duty cycle (dc) indicative of the ΔVBE is output by the 1-bit quantizer; and
the VBE1 that is stored on the capacitor is used as a reference voltage for the 1-bit DAC, thereby eliminating a need for a separate reference voltage to be trimmed and used as the reference voltage for the 1-bit DAC.

3. The method of claim 1 , wherein the producing the temperature measurement, based on the signal having the duty cycle (dc) indicative of the ΔVBE, comprises:
filtering the signal having the duty cycle (dc) indicative of the ΔVBE to thereby produce a digital value corresponding to the duty cycle (dc) indicative of the ΔVBE; and
using at least one of a processor, an equation, or a look up table (LUT), to produce the temperature measurement based on the digital value corresponding to the duty cycle (dc) indicative of the ΔVBE.

4. The method of claim 1 , wherein the diode device and the capacitor are components of an integrated circuit (IC) temperature sensor, and wherein the method further comprises:
producing a single calibration temperature measurement using the IC temperature sensor while the IC temperature sensor is in a location having a known temperature; and
performing a single point calibration of the IC temperature sensor using the single calibration temperature measurement.

5. The method of claim 4 , wherein:
the IC temperature sensor is for use within a specified temperature range of interest; and
the known temperature, of the location where the IC temperature sensor is located when the single calibration temperature measurement is produced, is outside the specified temperature range of interest, and thus, the single calibration temperature measurement used for the single point calibration is outside the specified temperature range of interest.

6. The method of claim 1 , wherein the temperature measurement is within +/−0.1° C. of an actual temperature.

7. The method of claim 1 , wherein the alternating between providing the first amount of current and the second amount of current to the same diode device comprises:
using each current source, of a group of N current sources, to produce a corresponding current that is substantially equal to the currents produced by the other current sources within the group, wherein N is ≥3; and
alternating between connecting one of the N current sources in the group to the diode device to thereby cause the providing of the first amount of current to the diode device, and connecting the N current sources in the group to the diode device to thereby cause the providing of the second amount of current to the diode device;
wherein which one of the N current sources is connected to the diode device, to thereby cause the providing of the first amount of current to the diode device, is changed in a round-robin, random, or pseudo-random manner so that small differences in the currents produced by the N current sources are averaged out over time.

8. The method of claim 1 , wherein the producing the signal having the duty cycle (dc) indicative of the ΔVBE includes:
based on an output of the 1-bit quantizer, selectively transferring a voltage equal to either C 1 *ΔVBE or −C 1 *VBE1 from the capacitor, which is part of both the integrator and the 1-bit DAC of the sigma-delta modulator, to a further capacitor of the integrator,
where C 1 is the value of the capacitor that is part of both the integrator and the 1-bit DAC of the sigma-delta modulator.

9. A temperature sensor for use in an implantable medical device (IMD), the temperature sensor comprising:
a diode device;
a plurality of current sources;
a controller configured to control alternating between providing a first amount of current and a second amount of current produced using the current sources, or subsets thereof, to the diode device, to thereby alternate between producing a first base-to-emitter voltage drop (VBE1) and a second base-to-emitter voltage drop (VBE2) using the same diode device; and
a sigma-delta modulator including a capacitor configured to alternate between storing the VBE1, which is complimentary to absolute temperature (CTAT), and storing a ΔVBE=VBE2−VBE1, which is proportion to absolute temperature (PTAT);
the sigma-delta modulator configured to produce a signal having a duty cycle (dc) indicative of the ΔVBE:
wherein the sigma-delta modulator includes a summing node, an integrator, a 1-bit quantizer, and a 1-bit digital-to-analog converter (DAC), the integrator including an operational amplifier (op-amp) having first and second inputs and an output, with one of the first and second inputs coupled to the summing node, and the integrator also including a switch between the output of the op-amp and an input of the 1-bit quantizer;
wherein the same capacitor that is used to store both the VBE1 and the ΔVBE is part of both the integrator and the 1-bit DAC of the sigma-delta modulator; and
wherein the switch is controlled to selectively couple the output of the op-amp to the input of the 1-bit quantizer.

10. The temperature sensor of claim 9 , wherein:
the summing node is coupled to a terminal of the diode device that alternately produces the VBE1 and the VBE2;
the signal having the duty cycle (dc) indicative of the ΔVBE is output by the 1-bit quantizer; and
the VBE1 that is stored on the capacitor is also used as a reference voltage for the 1- bit DAC, thereby eliminating a need for a separate reference voltage to be trimmed and used as the reference voltage for the 1-bit DAC.

11. The temperature sensor of claim 9 , wherein the sigma-delta modulator comprises a first order or higher order sigma-delta modulator.

12. The temperature sensor of claim 9 , further comprising:
a filter configured to filter the signal having the duty cycle (dc) indicative of the ΔVBE to thereby produce a digital value corresponding to the duty cycle (dc) indicative of the ΔVBE;

Assignees

• Pacesetter Inc

Inventors

• Opris Ion
• Andersen Dean

Classifications

• G01K7/01

  using semiconducting elements having PN junctions (G01K7/02, G01K7/16, G01K7/30 take precedence) · CPC title

• A61N1/3925

  Monitoring; Protecting · CPC title

• A61N1/39622

  Pacing therapy · CPC title

• A61B5/01 Primary

  Measuring temperature of body parts {; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue} (clinical contact thermometers G01K13/20) · CPC title

• G01K2219/00

  Thermometers with dedicated analog to digital converters · CPC title