Galvanic Isolator Having Improved High Voltage Common Mode Transient Immunity

Abstract

A galvanic isolator having a transmitter die, a receiver die, and a lead frame is disclosed. The transmitter die includes an LED having first and second contacts for powering the LED, and the receiver die includes a photodetector. The lead frame includes first and second transmitter leads, and first and second receiver leads. The transmitter die is bonded to the first lead, the first contact being connected electrically to the first transmitter lead and the second contact being connected to the second transmitter lead. The receiver die is connected to the first and second receiver leads. The LED and the photodetector are positioned such that light generated by the LED is received by the photodetector. The first and second transmitter leads are capacitively coupled to the first receiver lead. The capacitive couplings are characterized by first and second capacitance values that are substantially the same.

1 - 5 . (canceled) 
     
     
         6 . A galvanic isolator, comprising:
 a transmitter die comprising an LED having first and second contacts for powering said LED;   a receiver die comprising a photodetector;   a lead frame comprising first and second transmitter leads, and first and second receiver leads;   wherein said transmitter die is bonded to said first transmitter lead, said first contact is connected electrically to said first transmitter lead, said second contact is connected electrically to said second transmitter lead, said receiver die is connected electrically to said first and second receiver leads, said LED and said photodetector are positioned such that light generated by said LED is received by said photodetector, said first and second transmitter leads are capacitively coupled to said first receiver lead, said capacitive couplings are characterized by first and second capacitance values, said first and second capacitance values are substantially the same, and said second capacitance value is associated with a parasitic capacitance between said second transmitter lead and said first receiver lead.   
     
     
         7 . The galvanic isolator of  claim 6 , wherein said first capacitance value is associated with a parasitic capacitance between said first transmitter lead and said first receiver lead. 
     
     
         8 . The galvanic isolator of  claim 7 , wherein said transmitter is characterized by a minimum rise time for logic signals that are to be transmitted by said transmitter and said first and second capacitance values are selected such that a time constant associated with charging said first and second capacitors is less than said minimum rise time. 
     
     
         9 . The galvanic isolator of  claim 6 , wherein said transmitter die, said receiver die and a portion of said lead frame are contained within a package, said first receiver lead comprising first and second sections that are electrically isolated within said package and comprise external portions electrically isolated from one another but connectable by a conductor disposed outside of said package. 
     
     
         10 . The galvanic isolator of  claim 9 , wherein said second section is positioned to capacitively couple to said first transmitter lead more than to said second transmitter lead. 
     
     
         11 - 16 . (canceled) 
     
     
         17 . A galvanic isolator comprising:
 a transmitter die comprising an LED having first and second contacts for powering said LED:   a receiver die comprising a photodetector; and   a lead frame comprising first and second transmitter leads, and first and second receiver leads;   wherein said transmitter die is bonded to said first transmitter lead, said first contact is connected electrically to said first transmitter lead, said second contact is connected electrically to said second transmitter lead, said receiver die is connected electrically to said first and second receiver leads and bonded to said first receiver lead, said transmitter die and said receiver die are positioned such that light generated by said LED is received by said photodetector, said first transmitter lead comprises first and second sections, said first receiver lead comprises first and section sections, said transmitter die is bonded to said first section of said first transmitter lead, said receiver die is bonded to said first section of said first receiver lead, said first section of said first transmitter lead overlaps said first section of said first receiver lead and is separated therefrom by a first distance, said second section of said second transmitter lead overlaps said second section of said second receiver lead and is separated therefrom by a second distance, said first distance is less than said second distance said first sections are characterized by a first capacitance value, said second sections are characterized by a second capacitance value, and said second capacitance value is at least 1.3 times greater than said first capacitance value.   
     
     
         18 . A galvanic isolator comprising:
 a transmitter die comprising an LED having first and second contacts for powering said LED:   a receiver die comprising a photodetector; and   a lead frame comprising first and second transmitter leads, and first and second receiver leads;   
       wherein said transmitter die is bonded to said first transmitter lead, said first contact is connected electrically to said first transmitter lead, said second contact is connected electrically to said second transmitter lead, said receiver die is connected electrically to said first and second receiver leads and bonded to said first receiver lead, said transmitter die and said receiver die are positioned such that light generated by said LED is received by said photodetector, said first transmitter lead comprises first and second sections, said first receiver lead comprises first and section sections, said transmitter die is bonded to said first section of said first transmitter lead, said receiver die is bonded to said first section of said first receiver lead, said first section of said first transmitter lead overlaps said first section of said first receiver lead and is separated therefrom by a first distance, said second section of said second transmitter lead overlaps said second section of said second receiver lead and is separated therefrom by a second distance, said first distance is less than said second distance said first and second transmitter leads and said first receiver lead are shaped and positioned such that a first capacitance value between said first transmitter lead and said first receiver lead is substantially equal to a second capacitance value between said second transmitter lead and said second receiver lead. 
     
     
         19 . The galvanic isolator of  claim 17  or  claim 18 , wherein said photodetector comprises a photodiode and an amplifier. 
     
     
         20 . The galvanic isolator of  claim 17  or  claim 18 , wherein said photodetector comprises a phototransistor.