Method and apparatus for powering circuitry with on-chip solar cells within a common substrate

Abstract

A system and method for providing power to a light-powered transponder. In order to create a sufficient voltage differential, two different photovoltaic elements are used. The photovoltaic elements generate voltages of different polarities. Because the photovoltaic elements are used independently to generate voltages with different polarities, the present system can achieve a desired voltage differential despite the inherent difficulties presented by the use of a standard CMOS process.

What is claimed is:  
     
         1 . A power supply system for a photo-activated transponder, the system comprising: 
 a first photovoltaic power supply providing a voltage and    a second photovoltaic power supply providing a voltage with a different polarity than the voltage provided by the first power supply.    
     
     
         2 . The power supply system in  claim 1  wherein said first photovoltaic power supply supplies a positive voltage.  
     
     
         3 . The power supply system in  claim 1  wherein said second photovoltaic power supply supplies a negative voltage.  
     
     
         4 . The power supply system in  claim 1  wherein said transponder is manufactured using a CMOS process.  
     
     
         5 . The power supply system in  claim 1  further comprising a substrate connected with said first and second power supplies.  
     
     
         6 . The power supply system in  claim 5  wherein said substrate is P-type.  
     
     
         7 . The power supply system in  claim 6  wherein said first photovoltaic power supply comprises a P+implant in an N-well located in said substrate.  
     
     
         8 . The power supply system in  claim 6  wherein said second photovoltaic power supply comprises an N-well located in said substrate.  
     
     
         9 . The power supply system in  claim 6  wherein an N+ contact is located in said substrate.  
     
     
         10 . The power supply system in  claim 5  wherein said substrate is N-type.  
     
     
         11 . The power supply system in  claim 10  wherein said first photovoltaic power supply comprises an N+ implant in a P-well.  
     
     
         12 . The power supply system in  claim 10  wherein said first photovoltaic power supply comprises a P-well located in said substrate.  
     
     
         13 . The power supply system in  claim 10  wherein a P+ contact is located in said substrate.  
     
     
         14 . The power supply system in  claim 1  wherein said first supply is larger than said second supply.  
     
     
         15 . The power supply system in  claim 1  further comprising a third power supply.  
     
     
         16 . The power supply system in  claim 15  where said third power supply is operative to supply power to an antenna.  
     
     
         17 . The power supply in  claim 5  further comprising a third power supply connected with said substrate.  
     
     
         18 . The power supply in  claim 1  further comprising a load connected with said first and second photovoltaic power supplies.  
     
     
         19 . The power supply in  claim 18  wherein said load comprises digital logic circuitry  
     
     
         20 . The power supply in  claim 18  wherein said load comprises analog logic circuitry.  
     
     
         21 . A power supply apparatus for a photo-activated transponder, said power supply apparatus comprising: 
 a P-type substrate;    a first N-well connected with said P-type substrate;    an N+ contact connected with said first N-well operative to provide power with a negative voltage for a load.    a second N-well connected with said P-type substrate; and    a P+ contact connected with said second N-well operative to provide power with a positive voltage for said load.    
     
     
         22 . The power supply apparatus in  claim 21  further comprising a third n-well connected with said P-type substrate and a second N+ contact connected with said third N-well operative to provide power to an antenna.  
     
     
         23 . The power supply apparatus in  claim 21  further comprising a second N+ contact located in said P-type substrate operative to provide power to an antenna.  
     
     
         24 . A power supply apparatus for a photo-activated transponder, said power supply apparatus comprising: 
 an N-type substrate;    a first P-well connected with said N-type substrate;    a P+ contact connected with said first P-well operative to provide power with a positive voltage for a load.    a second P-well connected with said N-type substrate; and    an N+ contact connected with said second P-well operative to provide power with a negative voltage for said load.    
     
     
         25 . The power supply apparatus in  claim 24  further comprising a third P-well connected with said N-type substrate and a second P+ contact connected with said third P-well operative to provide power to an antenna.  
     
     
         26 . The power supply apparatus in  claim 24  further comprising a second P+ contact located in said substrate and operative to provide power to an antenna.  
     
     
         27 . A method for supplying power to a photo-activated transponder, said method comprising the acts of: 
 generating a positive voltage with a first photovoltaic element;    generating a negative voltage with a second photovoltaic element;    supplying power to a load with both said positive voltage and said negative voltage.    
     
     
         28 . The method of  claim 27  wherein the act of supplying power to a load with both said positive voltage and said negative voltage comprises supplying a voltage differential between two nodes, the voltage differential being greater than the individual positive and negative voltages.