Production-test die temperature measurement
A die temperature measurement system ( 300 ) includes an external test environment setup ( 352 ) and an integrated circuit ( 302 ). The external test environment setup ( 352 ) includes means to force and accurately measure electrical variables. The integrated circuit ( 302 ) includes a bipolar transistor ( 325 ); a selectable switch ( 340 ) for selecting from plurality of integrated resistances ( 342, 344 ) to be coupled in series between a base ( 322 ) of the bipolar transistor and a first input ( 362 ); and a selectable-gain current mirror ( 310 ) with a gain, a programmable current-mirror output coupled to the collector ( 326 ) of the bipolar transistor. The bipolar transistor and optional diodes ( 335 ) are sequentially biased with a set of proportional collector current levels. For each bias condition, the temperature-dependent voltage produced by the structure is extracted and stored. Die temperature is obtained through algebraic manipulation ( 450 ) of this data. Parasitic resistance and I/O pad leakage effects are canceled.
1. An integrated circuit including a temperature sensor circuit, comprising:
a temperature sensing circuit with a first (I/O) pad with a first routing resistance, a second input I/O pad with a second routing resistance, and a third I/O pad with a third routing resistance, the temperature sensing circuit including
a bipolar transistor including a base with a base parasitic resistance, a collector with a collector parasitic resistance, and an emitter with an emitter parasitic resistance, the first I/O pad coupled to the base, the second I/O pad coupled to the emitter, the third I/O pad coupled to the emitter;
a selectable switch for selecting from a plurality of integrated resistances to be coupled in series between the base of the bipolar transistor and first I/O pad;
a selectable-gain current mirror with a gain and a programmable current-mirror output coupled to the collector of the bipolar transistor.
2. The integrated circuit of claim 1 , further comprising:
at least one additional bipolar transistor coupled in series between an emitter of the bipolar transistor and the second I/O pad.
3. The temperature sensor of claim 2 , wherein the at least one additional bipolar transistor is coupled to form a diode.
4. A temperature sensor circuit, comprising:
a bipolar transistor including a base with a base parasitic resistance, a collector with a collector parasitic resistance, and an emitter with an emitter parasitic resistance;
a first I/O pad with a first routing resistance coupled to the base;
a second I/O pad with a second routing resistance coupled to the emitter;
a third I/O pad with a third routing resistance coupled to the emitter;
a selectable switch for selecting from a plurality of integrated resistances to be coupled in series between the base of the bipolar transistor and first I/O pad;
a selectable-gain current mirror with a gain and a programmable current-mirror output coupled to the collector of the bipolar transistor.
5. The temperature sensor circuit of claim 4 , further, comprising:
a driver with an input coupled to the collector of the bipolar transistor and an output coupled to the base of the bipolar transistor.
6. The temperature sensor of claim 4 , wherein at least one of the plurality of integrated resistances is approximately zero resistance.
7. The temperature sensor of claim 4 , further comprising:
at least one additional bipolar transistor coupled in series between an emitter of the bipolar transistor and the second I/O pad.
8. The temperature sensor of claim 7 , wherein the at least one additional bipolar transistor is coupled to form a diode.