Digital temperature sensor, corresponding device and method

A device comprising:

• a first circuit comprising:
• temperature sensing circuitry including first and second diode-connected transistors configured to produce a first signal indicative of a difference of voltage drops across the first and second diode-connected transistors and produce a second signal indicative of the voltage drop across the second diode-connected transistor, wherein the first signal and the second signal increase and decrease, respectively, with temperature, wherein the temperature sensed via the temperature sensing circuitry is a function of the first signal via a gain factor;
• a sigma-delta analog-to-digital converter coupled to the temperature sensing circuitry, the sigma-delta analog-to-digital converter having an output node configured to produce a pulsed output bitstream having a duty cycle that is a function of the first signal and the second signal via the gain factor;
• and
• a selection stage intermediate the temperature sensing circuitry and the sigma-delta analog-to-digital converter, wherein the selection stage is configured to operate in alternate first and second cycles under control of the pulsed output bitstream from the sigma-delta analog-to-digital converter to transfer to the sigma-delta analog-to-digital converter:
• during the first cycles, a first number of alternations of first signal transfer phases, wherein the first signal indicative of the difference of the voltage drops across the first and second diode-connected transistors is transferred with alternating signs to the sigma-delta analog-to-digital converter;
• and
• during the second cycles alternating with the first cycles, a second number of alternations of second signal transfer phases, wherein the second signal indicative of the voltage drop across the second diode-connected transistor is transferred with alternating signs to the sigma-delta analog-to-digital converter;
• wherein the gain factor is a function of a ratio of the first number of alternations to the second number of alternations;
• and
• a user circuit coupled to the first circuit and configured to be operated as a function of the pulsed output bitstream.

A method, comprising:

• producing, by first and second diode-connected transistors, a first signal indicative of a difference of voltage drops across the first and second diode-connected transistors, and producing a second signal indicative of the voltage drop across the second diode-connected transistor, the first signal and the second signal increasing and decreasing, respectively, with absolute temperature sensed being a function of the first signal via a gain factor;
• processing, by a sigma-delta analog-to-digital converter, the first signal and the second signal to produce a pulsed output bitstream having a duty cycle that is a function of the first signal and the second signal via the gain factor;
• and
• operating a selection stage, intermediate the first and second diode-connected transistors and the sigma-delta analog-to-digital converter, in alternate first and second cycles under control of the pulsed output bitstream to transfer to the sigma-delta analog-to-digital converter such that:
• during the first cycles, a first number of alternations of first signal transfer phases, the first signal indicative of the difference of the voltage drops across the first and second diode-connected transistors being transferred with alternating signs to the sigma-delta analog-to-digital converter;
• and
• during the second cycles alternating with the first cycles, a second number of alternations of second signal transfer phases, the second signal indicative of the voltage drop across the second diode-connected transistor being transferred with alternating signs to the sigma-delta analog-to-digital converter;
• the gain factor being a function of a ratio of the first number of alternations to the second number of alternations.