Isolation system with digital communication across a capacitive barrier Number:7,154,940 from the United States Patent and Trademark Office (PTO) owispatent 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. Finally, 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.<H communication, capacitive, Isolation, syste, 7154940.html, Patent, pto, 7154940

Title: Isolation system with digital communication across a capacitive barrier

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. Finally, 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.

Patent Number: 7,154,940 Issued on 12/26/2006 to Scott, et al.

Inventors: Scott; Jeffrey W. (Austin, TX), Sooch; Navdeep S. (Austin, TX), Welland; David R. (Austin, TX)
Assignee: Silicon Laboratories Inc. (Austin, TX)

Appl. No.: 10/606,231

Filed: June 25, 2003

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
09591684	Jun., 2000	6611553
08841409	Apr., 1997	6137827

Current U.S. Class: 375/220 ; 379/399.01; 379/412

Current International Class: H04B 1/38 (20060101)

Field of Search: 375/220 379/399.01,412

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Primary Examiner: Kim; Kevin
Attorney, Agent or Firm: O'Keefe, Egan & Peterman, LLP

Parent Case Text

This is a continuation of U.S. Ser. No. 09/591,684 filed on Jun. 9, 2000 now U.S. Pat. No. 6,611,553 entitled "Isolation System With Digital Communication Across A Capacitive Barrier" which is a continuation of U. S. Ser. No. 08/841,409 filed on Apr. 22, 1997 entitled "Isolation System With Digital Communication Across A Capacitive Barrier" (now U.S. Pat. No. 6,137,827).

Claims

We claim:

1. A bidirectional isolation system for providing an isolated communication channel for data signals in a forward direction and in a reverse direction across an isolation barrier comprised of a plurality of isolation elements, the system comprising: (a) a powered system on a first side of the isolation barrier, the powered system comprising a first driver circuit connected to the isolation barrier for driving a forward direction digital differential signal across at least two of the isolation barrier elements, the at least two isolation barrier elements comprising at least a first isolation capacitor and a second isolation capacitor; and (b) an isolated system on a second side of the isolation barrier, the isolated system comprising a second driver circuit connected to the isolation barrier for driving a reverse direction digital differential signal across the first isolation capacitor and the second isolation capacitor; wherein the forward direction digital differential signal and the reverse direction digital differential signal are both driven through the same first and second isolation capacitors so that the first and second isolation capacitors bidirectionally transfer the forward direction and reverse direction digital differential signals; wherein the isolated system receives power from the powered system from across the isolation barrier; and wherein the isolated system receives a clock signal from the powered system through at least one of the plurality of isolation elements.

2. The isolation system of claim 1, wherein the first and second driver circuits are differential driver circuits that drive the respective forward direction and reverse direction digital differential signals across the first and second isolation capacitors.

3. The isolation system of claim 1, wherein the first and second driver circuits are differential driver circuits.

4. The isolation system of claim 1 wherein the forward direction digital differential signal comprises said data signal multiplexed with a control signal.

5. The isolation system of claim 4, wherein the reverse direction digital differential signal comprises said data signal multiplexed with a control signal.

6. The isolation system of claim 1, wherein the isolated system receives a clock signal from the powered system through an isolation element that is separate from the first isolation capacitor and the second isolation capacitor.

7. The isolation system of claim 1, wherein at least one of the forward direction digital differential signal and the reverse direction digital differential signal includes both data and control information.

8. The isolation system of claim 1, wherein each of said plurality of isolation elements of said isolation barrier comprises a capacitor.

9. The isolation system of claim 1, wherein a portion of said plurality of isolation elements of said isolation barrier each comprises a capacitor.

10. A bidirectional isolation system for providing an isolated communication channel for data signals in a forward direction and in a reverse direction across an isolation barrier comprised of a plurality of isolation elements, the system comprising: (a) a powered system on a first side of the isolation barrier, the powered system comprising a first driver circuit connected to the isolation barrier for driving a forward direction digital differential signal across at least two of the isolation barrier elements, the at least two isolation barrier elements comprising at least a first isolation capacitor and a second isolation capacitor; and (b) an isolated system on a second side of the isolation barrier, the isolated system comprising a second driver circuit connected to the isolation barrier for driving a reverse direction digital differential signal across the first isolation capacitor and the second isolation capacitor; wherein the forward direction digital differential signal and the reverse direction digital differential signal are both driven through the same first and second isolation capacitors so that the first and second isolation capacitors bidirectionally transfer the forward direction and reverse direction digital differential signals; wherein the isolated system receives power from the powered system from across the isolation barrier to generate at least one power supply within the isolated system; wherein the isolated system receives a clock signal from the powered system through at least one of the plurality of isolation elements that is separate from the first isolation capacitor and the second isolation capacitor; and wherein at least one of the forward direction digital differential signal and the reverse direction digital differential signal includes both data and control information.

11. The isolation system of claim 10, wherein the first and second driver circuits are differential driver circuits that drive the respective forward direction and reverse direction digital differential signals across the first and second isolation capacitors.

12. The isolation system of claim 10, wherein the first and second driver circuits are differential driver circuits.

13. The isolation system of claim 10, wherein the forward direction digital differential signal comprises said data signal multiplexed with a control signal.

14. The isolation system of claim 13, wherein the reverse direction digital differential signal comprises said data signal multiplexed with a control signal.

15. The isolation system of claim 10, wherein each of said plurality of isolation elements of said isolation barrier comprises a capacitor.

16. The isolation system of claim 10, wherein a portion of said plurality of isolation elements of said isolation barrier each comprises a capacitor.

17. An isolation system for providing a digital communication channel for data signals and control signals, the isolation system comprising: an isolation barrier comprising a plurality of isolation elements; a first multiplexer located on one side of the isolation barrier and connected to receive the data signals and the control signals and providing a first multiplexed digital differential signal that is connected to at least two of the isolation barrier elements, the at least two isolation barrier elements comprising at least a first isolation capacitor and a second isolation capacitor; a first demultiplexer located on the other side of the isolation barrier and connected to receive the first multiplexed digital differential signal from the first isolation capacitor and the second isolation capacitor, wherein bidirectional communication exists through the first and second isolation capacitors and wherein the first demultiplexer has a data signal output and a control signal output; wherein one side of the isolation barrier is an isolated side that receives power from across the isolation barrier; and wherein the isolated side receives a clock signal from across the isolation barrier through at least one of the plurality of isolation elements.

18. The system of claim 17, further comprising a second multiplexer located on said other side of the isolation barrier and connected to receive data signals and control signals and providing a second multiplexed digital differential signal that is connected to the first isolation capacitor and the second isolation capacitor; a second demultiplexer located on said one side of the isolation barrier and connected to receive the second multiplexed digital differential signal from the first isolation capacitor and the second isolation capacitor, the second demultiplexer having a data signal output and a control signal output; whereby the first and second multiplexed digital differential signals are transmitted across the same first and second isolation capacitors so that bidirectional multiplexed communication of data and control signals across the isolation barrier is enabled.

19. The system of claim 17, wherein the first multiplexed digital differential signal includes both data information and control information.

20. The system of claim 18, wherein at least one of the first multiplexed digital differential signal and the second multiplexed digital differential signal includes both data information and control information.

21. The system of claim 17, wherein the isolated side receives a clock signal from across the isolation barrier through an isolation element that is separate from the first isolation capacitor and the second isolation capacitor.

22. The system of claim 17, wherein each of said plurality of isolation elements of said isolation barrier comprises a capacitor.

23. The system of claim 17, wherein a portion of said plurality of isolation elements of said isolation barrier each comprises a capacitor.

24. An isolation system for providing a digital communication channel for data signals and control signals, the isolation system comprising: an isolation barrier comprising a plurality of isolation elements; a first multiplexer located on one side of the isolation barrier and connected to receive the data signals and the control signals and providing a first multiplexed digital differential signal that is connected to at least two of the isolation barrier elements, the at least two isolation barrier elements comprising at least a first isolation capacitor and a second isolation capacitor, and wherein the first multiplexed digital differential signal includes both data information and control information; and a first demultiplexer located on the other side of the isolation barrier and connected to receive the first multiplexed digital differential signal from the first isolation capacitor and the second isolation capacitor, wherein bidirectional communication exists through the first and second isolation capacitors and wherein the first demultiplexer has a data signal output and control signal output, wherein one side of the isolation barrier is an isolated side that receives power from across the isolation barrier to generate at least one power supply; and wherein the isolated side receives a clock signal from across the isolation barrier through an isolation element that is separate from the first isolation capacitor and the second isolation capacitor.

25. The system of claim 24, further comprising a second multiplexer located on said other side of the isolation barrier and connected to receive data signals and control signals and providing a second multiplexed digital differential signal that is connected to the first isolation capacitor and the second isolation capacitor; a second demultiplexer located on said one side of the isolation barrier and connected to receive the second multiplexed digital differential signal from the first isolation capacitor and the second isolation capacitor, the second demultiplexer having a data signal output and a control signal output; whereby the first and second multiplexed digital differential signals are transmitted across the same first and second isolation capacitors so that bidirectional multiplexed communication of data and control signals across the isolation barrier is enabled.

26. The system of claim 24, wherein each of said plurality of isolation elements of said isolation barrier comprises a capacitor.

27. The system of claim 24, wherein a portion of said plurality of isolation elements of said isolation barrier each comprises a capacitor.

28. A bidirectional isolation system for providing an isolated communication channel for data signals in a forward direction and in a reverse direction across an isolation barrier