Crosstalk reduction in receiver inductive loop using capturing loop in transmitting inductive loop

Abstract

An inductively coupled multi-channel digital isolator where the transmitter and receiver inductive loops of a given channel are coplanar. In the case where two adjacent channels flow data in opposite directions, the receiver inductive loops of a given channel include a large, generally conventional loop portion and a small loop portion that is located inside the transmitter inductive loops of the adjacent channels. The sizes of the small loop portion and the conventional loop portion are generally in the ratio of the magnetic flux in the conventional loop portion to the magnetic flux in the transmitter inductive loop. This size relationship results in the voltage of the small loop portion being very close but opposite in sign to the voltage in the conventional loop portion. As a result, there is minimal crosstalk from the transmitter inductive loop of one channel to the receiver inductive loop of the adjacent channel.

1 . A multi-channel inductively coupled digital isolator comprising:
 a transmitter inductive loop; and   a receiver inductive loop inductively coupled to the transmitter inductive loop,   wherein the transmitter inductive loop and the receiver inductive loop are located adjacent each other, and   wherein the receiver inductive loop includes a portion of the loop inside the transmitter inductive loop.   
     
     
         2 . The digital isolator of  claim 1 , wherein the transmitter inductive loop and the receiver inductive loop are generally coplanar. 
     
     
         3 . The digital isolator of  claim 1 , wherein the transmitter inductive loop includes a plurality of turns of a conductor. 
     
     
         4 . The digital isolator of  claim 1 , wherein the receiver inductive loop includes a first portion having a plurality of turns of a conductor and a second portion forming the portion of the loop inside the transmitter inductive loop has at least one turn of a conductor. 
     
     
         5 . The digital isolator of  claim 4 , wherein a ratio of sizes of the first portion and second portion of the receiver inductive loop is substantially 
       
         
           
             
               
                 
                   B 
                   
                     + 
                     Y 
                   
                 
                 
                   B 
                   
                     - 
                     Y 
                   
                 
               
               = 
               
                 
                   A 
                   
                     X 
                     2 
                   
                 
                 
                   A 
                   
                     X 
                     1 
                   
                 
               
             
           
         
         where Y is the transmitter inductive loop, 
         where B is magnetic flux density, 
         where A is area, 
         where X2 is the first portion, and 
         where X1 is the second portion. 
       
     
     
         6 . The digital isolator of  claim 1 , wherein a Q of the receiver inductive loop with the portion of the loop inside the transmitter inductive loop is substantially the same as a receiver inductive loop without the portion of the loop inside the second channel transmitter inductive loop.