Temperature sensor with digital bandgap

Abstract

A system comprises a temperature sensor generate multiple base-emitter voltage signals by sequentially providing various currents to a transistor, and a system controller to determine a differential voltage signal according to the multiple base-emitter voltage signals, the differential voltage signal proportional to an environmental temperature associated with the transistor.

1 . A method comprising:
 generating multiple base-emitter voltage signals by sequentially providing various currents to a transistor;   determining a differential voltage signal according to the multiple base-emitter voltage signals, the differential voltage signal proportional to an environmental temperature associated with the transistor.   
     
     
         2 . The method of  claim 1   generating a first base-emitter voltage signal when a first current signal is provided to the transistor;   generating a second base-emitter voltage signal when a second current signal is provided to the transistor;   determining a difference between the first base-emitter voltage signal and the second base-emitter voltage signal;   determining the differential voltage signal, at least in part, according to the determined difference between the first base-emitter voltage signal and the second base-emitter voltage signal.   
     
     
         3 . The method of  claim 2  includes
 generating a third base-emitter voltage signal when a third current signal is provided to the transistor; 
 determining difference between at least one of the first base-emitter voltage signal and the third base-emitter voltage signal or the second base-emitter voltage signal and the third base-emitter voltage signal; and 
 determining the differential voltage signal, at least in part, according to the determined difference between at least one of the first base-emitter voltage signal and the third base-emitter voltage signal or the second base-emitter voltage signal and the third base-emitter voltage signal. 
 
     
     
         4 . The method of  claim 3  where determining the differential voltage signal includes averaging multiple differences determined between various base-emitter voltage signals. 
     
     
         5 . The method of  claim 3  where determining the differential voltage signal includes selecting one of the differences to represent the differential voltage signal. 
     
     
         6 . The method of  claim 1  where the multiple base-emitter voltage signals are analog base-emitter voltage signals; and
 converting the analog base-emitter voltage signals to digital base-emitter voltage signals for use in determining the differential voltage signal. 
 
     
     
         7 . The method of  claim 1  where converting the analog base-emitter voltage signals to digital base-emitter voltage signals is performed by a passive analog-to-digital converter. 
     
     
         8 . A system comprising:
 means for generating multiple base-emitter voltage signals by sequentially providing various currents to a transistor;   means for determining a differential voltage signal according to the multiple base-emitter voltage signals, the differential voltage signal proportional to an environmental temperature associated with the transistor.   
     
     
         9 . The method of  claim 8   means for generating a first base-emitter voltage signal when a first current signal is provided to the transistor;   means for generating a second base-emitter voltage signal when a second current signal is provided to the transistor;   means for determining a difference between the first base-emitter voltage signal and the second base-emitter voltage signal;   means for determining the differential voltage signal, at least in part, according to the determined difference between the first base-emitter voltage signal and the second base-emitter voltage signal.   
     
     
         10 . The method of  claim 9  including
 means for generating a third base-emitter voltage signal when a third current signal is provided to the transistor; 
 means for determining difference between at least one of the first base-emitter voltage signal and the third base-emitter voltage signal or the second base-emitter voltage signal and the third base-emitter voltage signal; and 
 means for determining the differential voltage signal, at least in part, according to the determined difference between at least one of the first base-emitter voltage signal and the third base-emitter voltage signal or the second base-emitter voltage signal and the third base-emitter voltage signal. 
 
     
     
         11 . The method of  claim 10  including means for averaging multiple differences determined between various base-emitter voltage signals to determine the differential voltage signal. 
     
     
         12 . The method of  claim 10  including means for selecting one of the differences to represent the differential voltage signal to determine the differential voltage signal. 
     
     
         13 . The method of  claim 8  where the multiple base-emitter voltage signals are analog base-emitter voltage signals; and
 means for converting the analog base-emitter voltage signals to digital base-emitter voltage signals for use in determining the differential voltage signal. 
 
     
     
         14 . A system comprising:
 a temperature sensor generate multiple base-emitter voltage signals by sequentially providing various currents to a transistor;   a system controller to determine a differential voltage signal according to the multiple base-emitter voltage signals, the differential voltage signal proportional to an environmental temperature associated with the transistor.   
     
     
         15 . The system of  claim 14  where the temperature sensor includes a variable current source to generate a first current signal and provide the first current signal to the transistor to generate a first base-emitter voltage signal, and to generate a second current signal and provide the second current signal to the transistor to generate a second base-emitter voltage signal. 
     
     
         16 . The system of  claim 15  where the variable current source includes a plurality of fixed current sources that are selectively activated when generating various current signals. 
     
     
         17 . The system of  claim 16  including a switch network to selectively couple one or more of the fixed current sources to the transistor. 
     
     
         18 . The system of  claim 17  where the temperature sensor includes a sequencer to direct the switch network to couple one or more of the fixed current sources to the transistor when prompted by the system controller. 
     
     
         19 . The system of  claim 15  where the system controller is configured to determine a difference between the first base-emitter voltage signal and the second base-emitter voltage signal, and to determine the differential voltage signal, at least in part, according to the determined difference between the first base-emitter voltage signal and the second base-emitter voltage signal. 
     
     
         20 . The system of  claim 14  including an analog-to-digital converter to convert base-emitter voltage signals to digital base-emitter voltage signals for use in determining the differential voltage signal, where the analog-to-digital is a passive converter.