Sensor circuit, corresponding system and method

A system comprising at least one digital temperature sensor, the digital temperature sensor comprising a circuit, the circuit comprising:

• a first current source configured to produce a first current in a first current line through a first diode-connected transistor having a voltage drop across the first diode-connected transistor, the first current being proportional to an absolute temperature via a first proportionality factor;
• a second current source configured to produce a second current in a second current line through a second diode-connected transistor having a voltage drop across the second diode-connected transistor, the second current being proportional to the absolute temperature via a second proportionality factor, the second proportionality factor being different from the first proportionality factor;
• a third current source configured to produce a third current in a third current line through a third diode-connected transistor having a voltage drop across the third diode-connected transistor;
• and
• a processing network comprising a sigma-delta analog-to-digital converter, the processing network being coupled to the first diode-connected transistor, the second diode-connected transistor, and the third diode-connected transistor, wherein an output bitstream at an output node from the sigma-delta analog-to-digital converter has an average value providing a temperature sensing signal with a linear dependency on temperature.

A method, comprising:

• producing a first current in a first current line through a first diode-connected transistor having a voltage drop across the first diode-connected transistor, the first current proportional to absolute temperature via a first proportionality factor;
• producing a second current in a second current line through a second diode-connected transistor having a voltage drop across the second diode-connected transistor, the second current proportional to absolute temperature via a second proportionality factor, the second proportionality factor different from the first proportionality factor;
• producing a third, temperature-independent, current in a third current line through a third diode-connected transistor having a voltage drop across the third diode-connected transistor;
• and
• applying sigma-delta analog-to-digital conversion processing with opposed signs on the following:
• a difference of the voltage drops across the first diode-connected transistor and the second diode-connected transistor;
• and
• a combination of the difference of the voltage drops across the second diode-connected transistor and the third diode-connected transistor and the voltage drop across the second diode-connected transistor, wherein an output bitstream from the sigma-delta analog-to-digital conversion processing has an average value providing a temperature sensing signal with a linear dependency on temperature.