Apparatus and method for termination powered differential interface periphery

• US 8,175,555 B2
• Filed: 05/07/2007
• Issued: 05/08/2012
• Est. Priority Date: 05/07/2007
• Status: Active Grant

• Current Assignee: Analogix Semiconductor, Inc. (Beijing Shanhai Capital Management Co., Ltd.)
• Original Assignee: Analogix Semiconductor, Inc. (Beijing Shanhai Capital Management Co., Ltd.)
• Inventors: Chi, Hongwu
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): Mehari, Yemane
• Application Number:
  US11/800,861
• Publication Number:
  US 20080278122A1
• Time in Patent Office: 1,828 Days
• Field of Search: 323/220, 323/234, 323/268, 326/82, 326/83, 326/86, 326/115, 327/538, 327/540, 327/541, 455 91-129
• US Class Current: 455/127.1
• CPC Class Codes: H03K 19/0008 Arrangements for reducing power consumption
• CPC Class Codes: H04L 25/0264 Arrangements for coupling to transmission lines duplexing arrangements H04L5/14; line equalisers, line build-out devices H04L25/03878
• CPC Class Codes: H04L 25/0272 Arrangements for coupling to multiple lines, e.g. for differential transmission
• CPC Class Codes: H04L 25/028 Arrangements specific to the transmitter end

Abstract

An apparatus and method for supplying power to the peripheral circuits of a transmitter circuit, especially an HDMI transmitter circuit, is disclosed. In an HDMI transmitter the termination resistors of the output driver are part of the receiver. DC power for the driver is supplied through these termination resistors. In prior art implementations of circuits this power, supplied by the receiver circuit, is wasted in the DC set-up circuit of the differential line driver. In various embodiments, this wasted power may be recovered from the remote termination to power selected peripheral circuits of the transmitter. The use of this wasted power may reduce the total system power consumption.

Claims

1. A power recovery circuit of a transmitter for recovering power from the terminating resistors of a termination power supply comprising:

a bias control circuit having at least a pair of current sensing and control elements coupled to connected sources of a differential driver pair to provide a predetermined bias to the connected sources, the differential driver pair being coupled to the terminating resistors;

a startup circuit coupled to the terminating resistors, the startup circuit enabled to provide an initial starting bias voltage and current to the bias control circuit when the termination power supply is enabled; and

a voltage regulator having an input coupled to an output of the bias control circuit to regulate an output voltage of the power recovery circuit;

the power recovery circuit using current supplied to the differential driver pair from the termination power supply and the voltage at the connected sources of the differential driver pair to provide regulated power from the voltage regulator to at least a portion of the peripheral circuits of the transmitter.

2. The power recovery circuit of claim 1 wherein the bias control circuit provides a predetermined bias to the connected sources by controlling power not used by the voltage regulator to supply power to the peripheral circuits.

3. The power recovery circuit of claim 1, further comprising:

a voltage booster coupled between the bias control circuit and the voltage regulator to step up the voltage to the voltage regulator.

4. The power recovery circuit of claim 1, wherein the terminating resistors are terminated in a remote receiver power supply.

5. The power recovery circuit of claim 4, wherein the receiver is an HDMI receiver.

6. The power recovery circuit of claim 1, wherein the transmitter is an HDMI transmitter.

7. The power recovery circuit of claim 1, wherein the current sensing and control elements comprise voltage controlled current sources.

8. The power recovery circuit of claim 7, wherein the voltage controlled current sources are selected from a group of elements comprising:

MOSFET devices and BJT devices.

9. The power recovery circuit of claim 1, wherein the startup circuit bleeds a small amount of power from the termination power supply to start the bias control circuit.

10. The power recovery circuit of claim 1, wherein the startup circuit is configured to be disabled from the bias control circuit once the bias conditions have been established.