Method and system for ESD protection of balanced circuit board lines

Abstract

An array of electrostatic discharge (ESD) devices conforms to the pitch defined by balanced signal lines on a printed wiring board (PWB) so that the array does not unduly affect the design impedance of the balanced lines.

1 . A printed wiring board (PWB), comprising: 
 at least one pair of balanced signal lines defining a pitch; and    at least one array of electrostatic discharge (ESD) devices electrically connecting each of the balanced signal lines to ground, the array conforming to the pitch.    
   
   
       2 . The PWB of  claim 1 , wherein the lateral distance between at least one of: successive ESD devices in the array, and successive ESD device traces, equals the pitch.  
   
   
       3 . The PWB of  claim 1 , wherein the pair of balanced signal lines includes first and second lines and the array includes first and second ESD devices respectively connected to the first and second lines, a ground being defined by the PWB, the first and second ESD devices being disposed on opposite sides of the ground from each other.  
   
   
       4 . The PWB of  claim 1 , comprising two pair of balanced signal lines carrying at least one of: universal serial bus (USB) signals, and IEEE-1394 signals.  
   
   
       5 . The PWB of  claim 1 , comprising three pair of balanced signal lines carrying IEEE-1394 signals and associated power line signals.  
   
   
       6 . The PWB of  claim 1 , comprising four pair of balanced signal lines carrying at least one of: Digital Visual Interface (DVI) signals, and High Definition Multimedia Interface (HDMI) signals.  
   
   
       7 . The PWB of  claim 1 , comprising four pair of balanced signal lines carrying DVI or HDMI signals and two lines carrying associated display data channel (DDC) signals.  
   
   
       8 . The PWB of  claim 1 , comprising at least one connector on the PWB and defining the pitch.  
   
   
       9 . The PWB of  claim 1 , wherein the array includes one and only one connection to ground established by at least one of: a lead on an end of the array, and a grounding pad on a surface of the array.  
   
   
       10 . An electrostatic discharge (ESD) device apparatus for a printed wiring board (PWB) having at least one pair of balanced signal lines, comprising: 
 plural ESD devices, one for each line in a pair of related balanced signal lines sought to be protected; and    plural traces, each trace respectively connected an ESD device, the balanced signal lines defining a pitch and the traces defining a pitch substantially equal to the pitch defined by the balanced signal lines.    
   
   
       11 . The ESD device apparatus of  claim 10 , wherein the balanced signal lines are associated with a design impedance, and at least the width of each trace is established such that the PWB with ESD device apparatus conforms to the design impedance.  
   
   
       12 . The ESD device apparatus of  claim 10 , wherein the balanced signal lines are associated with a design impedance, and at least the cross-sectional area of each trace is established such that the PWB with ESD device apparatus conforms to the design impedance.  
   
   
       13 . The ESD device apparatus of  claim 10 , wherein the pair of balanced signal lines includes first and second lines and the apparatus includes first and second ESD devices respectively connected to the first and second lines, a ground being defined by the PWB, the first and second ESD devices being disposed on opposite sides of the ground from each other.  
   
   
       14 . The ESD device apparatus of  claim 10 , comprising two pair of balanced signal lines carrying at least one of: universal serial bus (USB) signals, and IEEE-1394 signals.  
   
   
       15 . The ESD device apparatus of  claim 10 , comprising three pair of balanced signal lines carrying IEEE-1394 signals and associated power line signals.  
   
   
       16 . The ESD device apparatus of  claim 10 , comprising four pair of balanced signal lines carrying at least one of: Digital Visual Interface (DVI) signals, and High Definition Multimedia Interface (HDMI) signals.  
   
   
       17 . The ESD device apparatus of  claim 10 , comprising four pair of balanced signal lines carrying DVI or HDMI signals and two lines carrying associated display data channel (DDC) signals.  
   
   
       18 . The ESD device apparatus of  claim 10 , wherein the apparatus includes one and only one connection to ground established by at least one of: a lead on an end of an array of ESD devices, and a grounding pad on a surface of an array of ESD devices.  
   
   
       19 . A system, comprising: 
 at least one printed wiring board (PWB);    balanced signal line means on the PWB for carrying balanced signals; and    electrostatic discharge means operatively engaged with the balanced signal line means for shunting electrostatic surges to ground substantially without altering a design impedance of the balanced signal line means.