Multi-Channel Galvanic Isolator Utilizing a Single Transmission Channel

• US 20080198904A1
• Filed: 02/15/2007
• Published: 08/21/2008
• Est. Priority Date: 02/15/2007
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Chang, Kwee Chong
• Granted Patent: US 8,139,653 B2
• Time in Patent Office: Days
• US Class Current: 375/146
• CPC Class Codes: H01F 19/08 Transformers having magnetic bias, e.g. for handling pulses
• CPC Class Codes: H01F 2019/085 Transformer for galvanic isolation

Abstract

A galvanic isolator having a transmitting section and a receiving section is disclosed. The transmitting section includes a frame input circuit, a data encoder, and a data transmitter. The frame input circuit receives an input data frame that includes a plurality of input binary bits. The data encoder encodes the input binary bits to generate an encoded data frame that includes a sequence of encoded binary bits in which two successive encoded binary bits represent each input binary bit. The successive encoded binary bits representing a 1 are 01 or 10, and the successive encoded binary bits representing a 0 are 00 or 11. The sequences are chosen to maximize the number of transitions in the encoded data frame. A data receiver recovers the encoded data frame by examining successive pairs of encoded data bits using a clock that is reset on the edges in the encoded data frame.

Claims

1. A galvanic isolator comprising:

a transmitting section and a receiving section,

said transmitting section comprising;

a frame input circuit that receives an input data frame comprising a plurality of input binary bits;

a data encoder that encodes said input binary bits to generate an encoded data frame comprising a sequence of encoded binary bits in which two successive encoded binary bits represent each input binary bit, said successive encoded binary bits representing a 1 being 01 or 10 and said successive encoded binary bits representing a 0 being 00 or 11, wherein said sequences are chosen to maximize the number of transitions between successive bits having opposite values in said encoded data frame;

a data transmitter that transmits said encoded data frame across an isolation gap that electrically isolates said transmitting section and said receiving section; and

said receiving section comprising a data receiver that recovers said encoded data frame transmitted by said data transmitter;

a data decoder that examines successive pairs of recovered encoded data bits and generates a recovered output data bit from each of said successive pair of encoded data bits.

2. The galvanic isolator of claim 1 wherein said encoded data frame begins with a start frame signal comprising 0000 or 1111.

3. The galvanic isolator of claim 1 wherein said sequence of said start frame signal is chosen based on an encoded data bit in a previously transmitted encoded data frame.

4. The galvanic isolator of claim 1 wherein said encoded data frame comprises an ordered sequence of said encoded binary bits in which each encoded data bit corresponding to one of said input binary bits is immediately preceded by a previously encoded data bit and wherein said sequence of encoded binary bits representing a 1 is 01 if the previously encoded binary bit in said encoded data frame is a 1 and said sequence of binary bits representing a 1 is 10 if said previously encoded binary bit in said encoded data frame is a 0.

5. The galvanic isolator of claim 4 wherein said sequence of encoded binary bits representing a 0 is 00 if the previous encoded binary bit in said encoded data frame is a 1 and said sequence of binary bits representing a 0 is 11 if said previous encoded binary bit in said encoded data frame is a 0.

6. The galvanic isolator of claim 1 wherein said data decoder comprises a clock that is reset each time a pair of encoded binary bits corresponding to an input binary bit is received by said data decoder.

7. The galvanic isolator of claim 1 wherein said data decoder compares a pair of successive encoded binary bits to determine if those encoded binary bits are equal.

8. The galvanic isolator of claim 7 wherein said data decoder compares said pair of successive encoded bits by detecting a change in state in said encoded data frame in a time period defined by said clock that is reset each time a pair of encoded binary bits corresponding to an input binary bit is received by said data decoder.

9. The galvanic isolator of claim 2 wherein said data decoder compares three successive encoded binary bits to determine if a start frame signal has been received.

10. The galvanic isolator of claim 1 wherein said data transmitter comprises a light source and said data receiver comprises a photodetector.

11. The galvanic isolator of claim 1 wherein said data transmitter comprises an RF transmitter and said data receiver comprises an RF receiver.

12. The galvanic isolator of claim 1 wherein said data transmitter comprises one element of a split circuit element and said data receiver comprises a second element of said split circuit element.

13. The galvanic isolator of claim 12 wherein said split circuit element comprises a transformer having a primary coil in said transmitting section and a secondary coil in said data receiving section.

14. The galvanic isolator of claim 12 wherein said split circuit element comprises a capacitor having a first plate in said transmitting section and a second plate in said receiving section.