Temperature sensing with bandgap sensor input to sigma-delta adc

An integrated circuit including an integrated temperature sensor, 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 coupled to the first input node, and a second sampling capacitor coupled to 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 integrator output signal 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 integrator output signal,
• if the comparator output signal is a second value, then the sampled input ΔVBE voltage signal is added to the integrator output signal.

A method of sensing temperature in integrated circuits, comprising:

• providing from an integrated bandgap circuit a VBE voltage signal and a ΔVBE voltage signal;
• in successive integration cycles,
• cooperatively switching the ΔVBE voltage signal and the VBE voltage signal, in response respectively to a first switch control signal and a second switch control signal,
• sampling with a set of first and second sampling capacitors, either the ΔVBE voltage signal or the VBE voltage signal;
• and
• in each integration cycle,
• integrating either the sampled ΔVBE voltage signal or the sampled VBE voltage signal to generate a differential integrator output signal, and
• generating, based on a comparison of the differential integrator output signal, either a first comparison value or a second comparison value, and generating the first and second switch control signals such that:
• if the first comparison value, then the sampled VBE voltage signal is subtracted from the differential integrator output signal, and
• if the second comparison value, then the sampled ΔVBE voltage signal is added to the differential integrator output signal.