Method and apparatus for conveying bidirectional data, power and timing signals using a single transformer

• US 20050093731A1
• Filed: 10/31/2003
• Published: 05/05/2005
• Est. Priority Date: 10/31/2003
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Chaahoub, Faouzi, Beutler, Thomas G., Skov, James B., Patel, Ketankumar B.
• Granted Patent: US 7,881,461 B2
• Time in Patent Office: Days
• US Class Current: 341/155
• CPC Class Codes: H04L 25/0266 Arrangements for providing Galvanic isolation, e.g. by means of magnetic or capacitive coupling
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 7/0008 Synchronisation information channels, e.g. clock distribution lines
• CPC Class Codes: H04L 7/033 using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop
• CPC Class Codes: H04M 11/06 Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors

Abstract

Transformer driven by data modulated signal provides isolated power. Outbound data is extracted from the data modulated signal received from the transformer. Inbound data received in isolated circuitry modulates the load presented to transformer. Inbound data perceived in non-isolated circuitry by sensing load experienced by the transformer.

Claims

1. A method for conveying bidirectional data over a transformer comprising the steps of:

modulating an alternating current signal with outbound data;

driving a first side of the transformer with the modulated signal;

receiving the modulated signal from a second side of the transformer;

extracting outbound data from the received modulated signal;

modulating according to inbound data the load presented to the second side of the transformer when the alternating current signal is not modulated; and

receiving inbound data by sensing said load modulation.

2. The method of claim 1 wherein modulating the alternating current signal with outbound data comprises switching the phase of an alternating current signal according to a serial bit stream coincident with a clock.

3. The method of claim 1 wherein extracting outbound data comprises:

extracting a clock signal from the received modulated signal; and

sampling the received modulated signal according to the extracted clock signal.

4. The method of claim 3 wherein extracting a clock signal comprises:

sensing transitions in the received modulated signal;

generating an independent clock signal; and

synchronizing the independent clock with the transitions.

5. The method of claim 1 wherein modulating the load presented to the second side of the transformer comprises:

varying the impedance presented to the transformer according to a serial data stream coincident with an extracted clock signal.

6. The method of claim 1 further comprising:

generating an analog signal according to the extracted outbound data signal; and

varying the impedance of a circuit load according to the analog signal.

7. The method of claim 1 wherein modulating the load presented to the second side of the transformer comprises:

generating a digital value according to the voltage across a circuit load coincident with an extracted clock signal; and

varying the impedance presented to the second side of the transformer according to the digital value.

8. An apparatus for conveying bidirectional data across a galvanic barrier comprising:

signal generator;

signal modulator capable of modulating with outbound data a signal produced by the signal generator;

transformer having a first side capable of receiving a modulated signal from the signal modulator and a second side;

data extractor capable of extracting outbound data from a modulated signal received from the second side of the transformer;

transformer load modulator capable of modulating the load on the second side of the transformer according to inbound data; and

inbound data recovery unit capable of determining inbound data by sensing load modulations induced by the transformer load modulator.

9. The apparatus of claim 8 wherein the signal modulator comprises a phase modulator capable of altering the phase of the signal coincident with a clock.

10. The apparatus of claim 8 wherein the data extractor comprises:

clock extractor capable of extracting a clock from a received modulated signal; and

sampling device capable of sampling the received modulated signal according to the extracted clock.

11. The apparatus of claim 10 wherein the clock extractor comprises:

controllable oscillator capable of generating a clock according to a control signal; and

comparator capable of generating the control signal by comparing transitions in a received modulated signal with transitions in the generated clock.

12. The apparatus of claim 8 wherein the transformer load modulator comprises:

impedance element;

synchronizer capable of synchronizing inbound data with an extracted clock signal; and

switch capable of attaching the impedance element to the second side of the transformer according to the synchronized inbound data.

13. The apparatus of claim 8 further comprising:

digital-to-analog converter capable of generating an analog signal according to extracted outbound data;

line circuit load capable of presenting a load to a communications channel;

impedance element; and

analog gate capable of linearly imparting the impedance element across the line circuit load according to the analog signal.

14. The apparatus of claim 8 further comprising:

line circuit load capable of presenting a load to a communications channel;

analog-to-digital converter capable of generating a digital value according the voltage present across the line circuit load;

impedance element; and

switch capable of attaching the impedance element to the second side of the transformer according to the digital value.

15. A system-side isolation controller comprising:

signal generator;

signal modulator capable of modulating a signal produced by the signal generator; and

inbound data recovery unit capable of determining inbound data by sensing load modulations exhibited by a transformer.

16. The system-side isolation controller of claim 15 further comprising a transformer driver capable of driving the transformer with the modulated signal.

17. A line-side isolation controller comprising:

data extractor capable of extracting outbound data from a modulated signal received from a second side of a transformer; and

transformer load modulator capable of modulating the load presented to the second side of the transformer according to inbound data.

18. The line-side isolation controller of claim 17 wherein the data extractor comprises:

clock extractor capable of extracting a clock signal from a received modulated signal; and

sampling device capable of sampling the received modulated signal according to the extracted clock signal.

19. The line-side isolation controller of claim 18 wherein the clock extractor comprises:

controllable oscillator capable of generating a clock according to a control signal; and

comparator capable of generating the control signal by comparing transitions in a received modulated signal with transitions in the generated clock.

20. The line-side isolation controller of claim 17 further comprising:

digital-to-analog converter capable of generating an analog signal according to extracted outbound data;

analog gate capable of linearly imparting a first impedance element across a line circuit load according to the analog signal;

analog-to-digital converter capable of generating a digital value according the voltage present across the line circuit load;

impedance element; and

switch capable of attaching a second impedance element the second side of the transformer according to the digital value.