A circuit for temperature sensing receives a differential voltage that
corresponds to the voltage across a forward-biased PN junction. The
circuit for temperature sensing provides a first current to the PN
junction, and subsequently provides a second current. Also, the
temperature of the PN junction is determined based on the difference
between the differential voltage when the first current is applied and
the differential voltage when the second current is applied. Further, the
circuit for temperature sensing self-biases half of the differential
signal. The other half of the differential signal is level-shifted by an
amount that is fixed and predetermined based on the self-biasing to
provide a sub-ranging voltage. A sub-ranging analog-to-digital conversion
is performed on the differential voltage in which the sub-ranging voltage
is subtracted from the differential voltage during the conversion.