Temperature sensing with bandgap sensor input to sigma-delta ADC

Patent metadata

Field	Value
Publication number	US-10848175-B2
Application number	US-201916564059-A
Country	US
Kind code	B2
Filing date	Sep 9, 2019
Priority date	Mar 20, 2018
Publication date	Nov 24, 2020
Grant date	Nov 24, 2020

Abstract

In some examples, a sigma-delta analog-to-digital converter (ADC), comprises a first set of switches configured to receive a first voltage signal; a second set of switches coupled to the first set of switches at a first node and a second node, the second set of switches configured to receive a second voltage signal; an integrator including a first input sampling capacitor coupled to the first node and a second input sampling capacitor coupled to the second node, wherein the integrator configured to generate a first output signal. The sigma-delta ADC further comprises a comparator coupled to the integrator and configured to generate a second output signal based on the first output signal; and a controller unit having a first counter, a second counter, and a processor, the controller unit coupled to the first and second sets of switches, the integrator, and the comparator.

First claim

The invention claimed is:

1. A circuit for sensing temperature in integrated circuits, comprising:
a bandgap circuit to provide a VBE voltage signal and a ΔVBE voltage signal;
a set of first input switches coupled respectively to a first input node and a second input node, the first input switches to receive the ΔVBE voltage signal;
a set of second input switches coupled respectively to the first input node and the second input node, the second input switches to receive the VBE voltage signal;
a sigma delta analog to digital converter (ADC), including
an integrator including a first sampling capacitor and a second sampling capacitor, respectively coupled to the first input node and the second input node, the integrator to generate differential integrator output signals, and
a comparator coupled to the integrator and configured to generate a comparator output signal based on the differential integrator output signals; and

the first input switches controllable by a first switch control signal to provide to the first and second nodes an input ΔVBE voltage signal;
the second input switches controllable by a feedback digital control signal to operate as digital-to-analog converter (DAC) circuitry to provide to the first and second input nodes an input VBE voltage signal;
the integrator to generate the differential integrator output signals based on sampling with the first and second sampling capacitors either the input ΔVBE voltage signal or the input VBE voltage signal; and
a controller unit coupled to the first and second input switches, the integrator, and the comparator, the controller unit operable in each of successive integration cycles to generate the first switch control signal and the feedback digital signal such that:
if the comparator output signal is a first value, then the sampled input VBE voltage signal is subtracted from the differential integrator output signals,

if the comparator output signal is a second value, then the sampled input ΔVBE voltage signal is added to the differential integrator output signals;
wherein the controller unit is configured to determine a temperature value based on ΔVBE/VREF, where ΔVBE is a value based on the input ΔVBE voltage signal, and VREF is a reference value generated by scaling a value based on the input VBE voltage signal;
wherein the controller unit includes a ΔVBE counter associated with the input ΔVBE voltage signal, and a VBE counter associated with the input VBE voltage signal, and is configured:

if the comparator output signal is the first value, so that the sampled input VBE voltage signal is subtracted from the differential integrator output signals, to increment the ΔVBE counter value by a defined scale factor P, and the VBE counter value by 1, and
if the comparator output signal is the second value, so that the sampled input ΔVBE voltage signal is added to the differential integrator output signals, to increment the ΔVBE counter value by the 1, and the VBE counter value by 0; and
to generate the temperature value based on the ΔVBE counter value and the VBE counter value according to:
Δ VBE/V REF= N /[ K +( P*N )]

where N=VBE counter value, and K=ΔVBE counter value.

2. A circuit for sensing temperature in integrated circuits, comprising:
a bandgap circuit to provide a VBE voltage signal and a ΔVBE voltage signal;
a set of first input switches coupled respectively to a first input node and a second input node, the first input switches to receive the ΔVBE voltage signal;
a set of second input switches coupled respectively to the first input node and the second input node, the second input switches to receive the VBE voltage signal;
a sigma delta analog to digital converter (ADC), including
an integrator including a first sampling capacitor and a second sampling capacitor, respectively coupled to the first input node and the second input node, the integrator to generate differential integrator output signals, and
a comparator coupled to the integrator and configured to generate a comparator output signal based on the differential integrator output signals; and

the first input switches controllable by a first switch control signal to provide to the first and second nodes an input ΔVBE voltage signal;
the second input switches controllable by a feedback digital control signal to operate as digital-to-analog converter (DAC) circuitry to provide to the first and second input nodes an input VBE voltage signal;
the integrator to generate the differential integrator output signals based on sampling with the first and second sampling capacitors either the input ΔVBE voltage signal or the input VBE voltage signal; and
a controller unit coupled to the first and second input switches, the integrator, and the comparator, the controller unit operable in each of successive integration cycles to generate the first switch control signal and the feedback digital signal such that:
if the comparator output signal is a first value, then the sampled input VBE voltage signal is subtracted from the differential integrator output signals,

if the comparator output signal is a second value, then the sampled input ΔVBE voltage signal is added to the differential integrator output signals;
wherein the controller unit is configured to perform a defined number of integration cycles M;
wherein after performing the defined number of integration cycles M, the controller unit is configured to perform an additional number of integration cycles until the comparator output signal is the first value, limiting a residue value to a range of zero to −ΔVBE.

3. The temperature sensor of claim 2 , wherein, after the additional number of integration cycles, the controller unit and the integrator are configured to perform a cyclic successive approximation operation to quantify a ratio of the residue value to the input ΔVBE voltage, including doubling the residue value and comparing the magnitude to the input ΔVBE voltage.

4. A circuit for sensing temperature in integrated circuits, comprising:
a bandgap circuit to provide a VBE voltage signal and a ΔVBE voltage signal;
a set of first input switches coupled respectively to a first input node and a second input node, the first input switches to receive the ΔVBE voltage signal;
a set of second input switches coupled respectively to the first input node and the second input node, the second input switches to receive the VBE voltage signal;
a sigma delta analog to digital converter (ADC), including
an integrator including a first sampling capacitor and a second sampling capacitor, respectively coupled to the first input node and the second input node, the integrator to generate differential integrator output signals, and
a comparator coupled to the integrator and configured to generate a comparator output signal based on the differential integrator output signals; and

the first input switches controllable by a first switch control signal to provide to the first and second nodes an input ΔVBE voltage signal;
the second input switches controllable by a feedback digital control signal to operate as digital-to-analog converter (DAC) circuitry to provide to the first and second input nodes an input VBE voltage signal;
the integrator to generate the differential integrator output signals based on sampling with the first and second sampling capacitors either the input ΔVBE voltage signal or the input VBE voltage signal; and
a controller unit coupled to the first and second input switches, the integrator, and the comparator, the controller unit operable in each of successive integration cycles to generate the first switch control signal and the feedback digital signal such that:
if the comparator output signal is a first value, then the sampled input VBE voltage signal is subtracted from the differential integrator output signals

Assignees

• Texas Instruments Inc

Inventors

• Doorenbos Jerry Lee
• Sanborn Keith Eric
• Vellore Avadhanam Ramamurthy Srikanth
• Nashed Mina Raymond Naguib
• Griffin Dwight David

Classifications

• H03M3/38 Primary

  Calibration · CPC title

• H03M3/494 Primary

  Sampling or signal conditioning arrangements specially adapted for delta-sigma type analogue/digital conversion systems · CPC title

• H03M3/466

  Multiplexed conversion systems · CPC title

• H03M3/464

  Details of the digital/analogue conversion in the feedback path · CPC title

• G01K2219/00

  Thermometers with dedicated analog to digital converters · CPC title