Direct digital access arrangement circuitry and method for connecting DSL circuitry to phone lines

Abstract

An isolation system is provided that is suitable for use in telephony, medical instrumentation, industrial process control and other applications. Preferred embodiments of the invention comprise a capacitive isolation barrier across which a digital signal is communicated. The system provides a means of communication across the isolation barrier that is highly immune to amplitude and phase noise interference. Clock recovery circuitry may be employed on one side of the isolation barrier to extract timing information from the digital signal communicated across the barrier, and to filter the effects of phase noise introduced at the barrier. Delta-sigma converters may be disposed on both sides of the isolation barrier to convert signals between analog and digital domains. An isolated power supply may also be provided on the isolated side of the barrier, whereby direct current is generated in response to the digital data received across the isolation barrier. A bidirectional isolation system is provided whereby bidirectional communication of digital signals is accomplished using a single pair of isolation capacitors. In preferred embodiments, the digital data communicated across the barrier consists of digital delta-sigma data signals multiplexed in time with other digital control, signaling and framing information. Finally, the isolation system may include a pulse transformer to accommodate ADSL circuitry, whereby power is transmitted through the pulse transformer.

1 . Circuitry for terminating a phone line connection, comprising: 
 powered side circuitry operable to communicate digitally with phone line side circuitry, said digital communication comprising a digital data stream;    phone line side circuitry operable to communicate digitally with powered side circuitry, said digital communication between said powered side circuitry and said phone line side circuitry comprising a digital data stream transmitted through an isolation barrier; and    encode and decode circuitry coupled to said digital data stream to generate an encoded digital signal for transmission and receipt across said isolation barrier.    
   
   
       2 . The circuitry of  claim 1 , further comprising DSL circuitry that may be used to generate DSL information for transmission across said isolation barrier.  
   
   
       3 . The circuitry of  claim 2 , wherein said isolation barrier is comprised of one or more capacitors.  
   
   
       4 . The circuitry of  claim 2 , wherein said isolation barrier is comprised of a transformer and one or more capacitors.  
   
   
       5 . The circuitry of  claim 4 , wherein said transformer is comprised of a pulse transformer.  
   
   
       6 . The circuitry of  claim 2 , wherein said phone line side circuitry further comprises phone line side DSL circuitry that may be used for receiving said DSL information transmitted across said isolation barrier.  
   
   
       7 . The circuitry of  claim 6 , wherein said isolation barrier is comprised of a transformer.  
   
   
       8 . The circuitry of  claim 7 , wherein said transformer powers said phone line side DSL circuitry.  
   
   
       9 . The circuitry of  claim 7 , wherein said DSL information is transmitted across said transformer.  
   
   
       10 . A method of operating circuitry for terminating a phone line connection, comprising: 
 providing phone line side circuitry operable to communicate with a capacitive isolation barrier and the phone line connection;    utilizing digital information transmitted across the capacitive isolation barrier to provide a phone line side clock; and    utilizing digital information transmitted across the capacitive isolation barrier to provide a power supply for at least a portion of the phone line side circuitry.    
   
   
       11 . The method of  claim 10 , wherein said phone line side circuitry further comprises DSL circuitry that may be used for receiving DSL information transmitted across said capacitive isolation barrier.  
   
   
       12 . The method of  claim 11 , wherein said capacitive isolation barrier is comprised of a plurality of capacitors.  
   
   
       13 . The method of  claim 11 , wherein said capacitive isolation barrier is comprised of at least one transformer and one or more capacitors.  
   
   
       14 . The method of  claim 13 , wherein said transformer is comprised of a pulse transformer.  
   
   
       15 . The method of  claim 11  further comprising providing powered side circuitry, wherein said powered side circuitry further comprises powered side DSL circuitry that may be used for transmitting DSL information across said capacitive isolation barrier.  
   
   
       16 . The method of  claim 15 , wherein said capacitive isolation barrier is comprised of at least one transformer.  
   
   
       17 . The method of  claim 16 , wherein said transformer powers said DSL circuitry.  
   
   
       18 . The method of  claim 16 , wherein said DSL information is transmitted across said transformer.  
   
   
       19 . Circuitry for terminating a phone line connection, comprising: 
 powered side circuitry operable to communicate digitally with phone line side circuitry, said digital communication comprising a digital data stream transmitted across a isolation barrier through a first bi-directional connection; the isolation barrier including at least one capacitor and    phone line side circuitry operable to communicate digitally with powered side circuitry, said digital communication comprising a digital data stream transmitted across said isolation barrier through a second bidirectional connection.    
   
   
       20 . The circuitry of  claim 19 , wherein said powered side circuitry further comprises powered side DSL circuitry and said phone line side circuitry further comprises phone line side DSL circuitry.  
   
   
       21 . The circuitry of  claim 20 , wherein said isolation barrier comprises a plurality of capacitors.  
   
   
       22 . The circuitry of  claim 21 , wherein said isolation barrier further comprises a transformer.  
   
   
       23 . The circuitry of  claim 22 , wherein said transformer is a pulse transformer.  
   
   
       24 . The circuitry of  claim 22 , wherein said transformer powers said phone line side DSL circuitry.  
   
   
       25 . The circuitry of  claim 22 , wherein said powered side DSL circuitry includes encode circuitry to generate an encoded digital DSL signal for transmission across said isolation barrier and wherein said phone line side DSL circuitry includes decode circuitry to generate a decoded digital DSL signal from said encoded digital DSL signal.  
   
   
       26 . A method for communicating with phone lines, comprising: 
 converting a digital signal into a digital data stream;    communicating said digital data stream across an isolation barrier from a bi-directional connection on powered side circuitry to a bi-directional connection on phone line side circuitry, said communication being bidirectional through at least one capacitive element; and    utilizing the digital data stream to generate a power supply within the phone line side circuitry.    
   
   
       27 . The method of  claim 26 , wherein said powered side circuitry includes powered side DSL circuitry and wherein said phone line side circuitry includes phone line side DSL circuitry.  
   
   
       28 . The method of  claim 27 , wherein said isolation barrier comprises a plurality of capacitors.  
   
   
       29 . The method of  claim 28 , wherein said isolation barrier further comprises a transformer.  
   
   
       30 . The method of  claim 29 , wherein said phone line side DSL circuitry is powered by said transformer.  
   
   
       31 . Circuitry for terminating a phone line connection, comprising: 
 powered side circuitry operable to communicate digitally with phone line side circuitry through a first node capable of communicating with a capacitive isolation barrier;    phone line side circuitry operable to communicate digitally with the powered side circuitry through a second node capable of communicating with the capacitive isolation barrier;    a clock signal within the phone line side circuitry, the clock signal capable of being generated from information transmitted across the capacitive isolation barrier;    at least one power supply within the phone line side circuitry, the power supply capable of being generated from information transmitted across the capacitive isolation barrier; and    at least one control signal within the phone line side circuitry, the control signal being capable of being transmitted across the capacitive isolation barrier.    
   
   
       32 . The circuitry of  claim 31 , wherein the powered side circuitry further comprises powered side DSL circuitry and the phone line side circuitry further comprises phone line side DSL circuitry.  
   
   
       33 . The circuitry of  claim 32 , wherein the capacitive isolation barrier further comprises a transformer.  
   
   
       34 . The circuitry of  claim 33 , wherein the transformer is a pulse transformer.  
   
   
       35 . The circuitry of  claim 33 , wherein said phone line side DSL circuitry is powered by said transformer.