Patent ID: 7170334

Claim:
A temperature sensing circuit, comprising: a bipolar transistor (BJT); a forced emitter current I E of the form I fixed +I fixed /β, where β is the BJT's β value, such that said BJT's base current is given by I fixed /β and its collector current is given by I fixed +I fixed /β−I fixed /β=I fixed ; a current mirror circuit which mirrors said base current I fixed /β to said emitter; and a current source which provides an output current I fixed that switches between a first value I and a second value N*I such that said BJT's base-emitter voltage has a first value V be1 when I fixed =I and a second value V be2 when I fixed =N*I, such that: ΔV be21 =V be2 −V be1 =( n F kT/q )(ln N), where n F is the BJT's emission coefficient, k is Boltzmann's constant, T is absolute temperature in degrees Kelvin, and q is the electron charge.