On chip temperature measuring and monitoring circuit and method

Abstract

A device temperature measurement circuit, an integrated circuit (IC) including a device temperature measurement circuit, a method of characterizing device temperature and a method of monitoring temperature. The circuit includes a constant current source and a clamping device. The clamping device selectively shunts current from the constant current source or allows the current to flow through a PN junction, which may be the body to source/drain junction of a field effect transistor (FET). Voltage measurements are taken directly from the PN junction. Junction temperature is determined from measured junction voltage.

1 . An integrated circuit (IC) comprising: 
 a plurality of devices connected together and forming circuits;    a switchable current source selectively providing a known current to a PN junction in at least one of said plurality of devices, said switchable current source comprising: 
 a constant current source, and  
 a clamping device selectively shunting current from said constant current source; and  
   a voltage measurement circuit measuring voltage across said PN junction, measured said voltage corresponding to PN junction temperature.    
   
   
       2 . (canceled)  
   
   
       3 . An IC as in  claim 1 , wherein said voltage measurement circuit comprises an analog to digital converter.  
   
   
       4 . An IC as in  claim 1 , wherein said voltage measurement circuit comprises a comparator.  
   
   
       5 . An IC as in  claim 4 , wherein a reference voltage is provided to said comparator for comparison against said voltage across said PN junction.  
   
   
       6 . An IC as in  claim 1 , wherein said plurality of devices includes a plurality of field effect transistors (FETs) and said PN junction is a FET body to source/drain junction.  
   
   
       7 . An IC as in  claim 6 , wherein said IC is on a silicon on insulator chip and said plurality of FETs comprises a plurality of P-type FETs (PFETs) and a plurality of N-type FETs (NFETs) connected together in CMOS circuits.  
   
   
       8 . (canceled)  
   
   
       9 . An IC as in  claim 7 , wherein said voltage measurement circuit comprises an analog to digital converter.  
   
   
       10 . An IC as in  claim 7 , wherein said voltage measurement circuit comprises a comparator.  
   
   
       11 . An IC as in  claim 10 , wherein a reference voltage is provided to said comparator for comparison against said voltage across said PN junction.  
   
   
       12 - 31 . (canceled)  
   
   
       32 . An integrated circuit (IC) comprising: 
 a plurality of devices connected together and forming circuits;    a switchable current source selectively providing a known current to a PN junction in at least one of said plurality of devices, said switchable current source comprising: 
 a constant current source, and  
 a clamping device in parallel with said constant current source and selectively shunting current from said constant current source through said clamping device; and  
   a voltage measurement circuit measuring voltage across said PN junction, measured said voltage corresponding to PN junction temperature.