Transmitting circuit, receiving circuit, interface switching module and interface switching method for SATA and SAS interfaces

• US 7,840,194 B2
• Filed: 10/13/2006
• Issued: 11/23/2010
• Est. Priority Date: 10/18/2005
• Status: Active Grant

• Current Assignee: Sunplus Technology Co., Ltd
• Original Assignee: Sunplus Technology Co., Ltd
• Inventors: Chou, Min-Chung, Wu, Yu-Hsin, Lin, Hung-Chih
• Primary Examiner(s): Dao, Minh D
• Application Number:
  US11/546,919
• Publication Number:
  US 20070115954A1
• Time in Patent Office: 1,502 Days
• Field of Search: 455/107, 455/248.1, 455/78, 455/83, 455/13.3, 455/191.3, 455/63.3, 455/320, 455/330, 375/219, 375/249, 370/356, 370/401
• US Class Current: 455/107
• CPC Class Codes: G06F 13/4072 Drivers or receivers G06F13/4086 takes precedence; for multistate logic circuits H03K19/0002

Abstract

A transmitter circuit, a receiver circuit and an interface switching module for SATA or SAS interface are provided. The invention uses transistors as elements with different impedance and also provides impedance modulating method in coordination with the exterior circuit and the layout design so as to develop an auto-switching mechanism between SATA and SAS interfaces, thereby integrating two transmission interfaces in a single system.

Claims

1. A transmitting circuit for a serial transmission interface that receives a transmitting data signal to generate a pair of transmitting signals, comprising:

a first resistor unit controlled by a control signal, wherein the first resistor unit has a predetermined impedance value while the control signal is enabled, or has a high-impedance value while the control signal is disabled;

a first switch unit connected to the first resistor unit and controlled by the transmitting data signal, wherein the connecting node of the first switch unit and the first resistor unit is defined as a first terminal;

a second resistor unit controlled by the control signal, wherein the second resistor unit has the predetermined impedance value while the control signal is enabled or has the high impedance value while the control signal is disabled;

a second switch unit connected to the second resistor unit and controlled by the reverse signal of transmitting data signal, wherein the connecting node of the second switch unit and the second resistor unit is defined as a second terminal; and

an auto-detection circuit for generating the control signal according to a reference signal;

wherein the pair of transmitting signals are output from the first terminal and the second terminal, and the pair of transmitting signals are determined by the transmitting data signal while the control signal is enabled, or the pair of transmitting signals are at a high impedance state without output from the first terminal and the second terminal while the control signal is disabled.

2. The transmitting circuit of claim 1, wherein the first resistor unit and the second resistor unit are transistors having gates receiving the control signal, drains being connected to a voltage source and sources being defined as the first terminal and the second terminal respectively.

3. The transmitting circuit of claim 1, wherein the first resistor unit and the second resistor unit both comprise:

a resistor having the predetermined impedance value, wherein one terminal of the resistor is connected to a voltage source; and

a transistor having a gate receiving the control signal, a drain being connected to the other terminal of the resistor, and a source being defined as the first terminal and the second terminal respectively.

4. The transmitting circuit of claim 1, wherein the first resistor unit and the second resistor unit both comprise:

a transistor having a gate receiving the control signal and a drain being connected to a voltage source; and

a resistor, having the predetermined impedance value, wherein one side of the resistor is connected to a source of the transistor, and the other side of the resistor is defined as the first terminal and the second terminal.

5. The transmitting circuit of claim 1, wherein the first switch unit and the second switch unit are transistors, the transistors having gates receiving the transmitting data signal and the reverse signal of the transmitting data signal respectively, drains being connected to the first resistor unit and the second resistor unit respectively, and sources being connected to a current source.

6. A receiving circuit for a serial transmission interface that receives a first receiving signal and a second receiving signal to generate a receiving data signal, comprising:

a first resistor unit for receiving the first receiving signal and a control signal, wherein the first resistor unit has a predetermined impedance value while the control signal is enabled, or has a high impedance value while the control signal is disabled;

a second resistor unit for receiving the second receiving signal and the control signal, wherein the second resistor unit has the predetermined impedance value while the control signal is enabled, or has the high impedance value while the control signal is disabled;

a first receiving unit, responsive to the first receiving signal, for generating a first differential signal;

a second receiving unit, responsive to the second receiving signal, for generating a second differential signal;

a differential amplifier for receiving the first differential signal and the second differential signal and generating the receiving data signal; and

an auto-detection circuit for generating the control signal according to a reference signal;

wherein both the first resistor unit and the second resistor unit have the high impedance values such that the first receiving signal and the second receiving signal are incapable of passing through the first resistor unit and the second resistor unit respectively while the control signal is disabled.

7. The receiving circuit of claim 6, wherein the first resistor unit and the second resistor unit are transistors having gates receiving the control signal, drains respectively receiving the first receiving signal and the second receiving signal and sources being connected to ground.

8. The receiving circuit of claim 6, wherein the first resistor unit and the second resistor unit both comprise.

a resistor having the predetermined impedance value, one terminal of the resistor receiving the first receiving signal and the second receiving signal respectively;

and

a transistor having a gate receiving the control signal, a drain being connected to the other terminal of the resistor and a source being connected to ground.

9. The receiving circuit of claim 6, wherein the first resistor unit and the second resistor unit both comprise:

a transistor having a gate for receiving the control signal and a drain for receiving the first receiving signal and the second receiving signal respectively; and

a resistor having a resistance value equal to the predetermined impedance value, wherein one terminal of the resistor is connected to a source of the transistor, and the other terminal of the resistor is connected to ground.

10. The receiving circuit of claim 6, wherein the first receiving unit and the second receiving unit are transistors, the transistors having gates respectively receiving the first receiving signal and the second receiving signal, drains being connected to a current source, and sources being connected to ground.

11. An interface switching module for a system with two serial transmission interfaces, comprising:

a first interface connector having two first transmitting pins for delivering a pair of transmitting signals, two first receiving pins for delivering a pair of receiving signals, and a plurality of first ground pins connected to the ground terminal of the system;

a second interface connector having two second transmitting pins connected to the first transmitting pins, two second receiving pins connected to the first receiving pins, a control pin and a plurality of second ground pins connected to the ground terminal of the system, wherein the control pin is grounded when a plug is plugged into the second interface connector, otherwise the control pin is floated; and

a transceiver circuit for generating the pair of transmitting signals to the first interface connector and for receiving the pair of receiving signals from the first interface connector when the control pin is floated.

12. The interface switching module of claim 11, wherein the system is a cascaded redundant arrays of independent disks (RAID) with serial ATA (SATA).

13. The interface switching module of claim 11, wherein the transceiver circuit generates the pair of transmitting signals according to a transmitting data signal, and also generates a receiving data signal according to the pair of receiving signals, the transceiver circuit comprising:

an auto-detection circuit for generating a control signal according to the potential of the control pin;

a first resistor unit controlled by the control signal, wherein the first resistor unit has a predetermined impedance value while the control signal is enabled or has a high impedance value while the control signal is disabled;

a first switch unit connected to the first resistor unit and controlled by the transmitting data signal, wherein the connecting node of the first switch unit and the first resistor unit is defined as a first terminal;

a second resistor unit controlled by the control signal, wherein the second resistor unit has the predetermined impedance value while the control signal is enabled or has a high-impedance value while the control signal is disabled;

a second switch unit connected to the second resistor unit and controlled by the reverse signal of transmitting data signal, wherein the connecting node of the second switch unit and the second resistor unit is defined as a second terminal;

a third resistor unit for receiving one of the receiving signals and the control signal, that has the predetermined impedance value while the control signal is enabled, or has the high impedance value while the control signal is disabled;

a fourth resistor unit for receiving the other of the receiving signals and the control signal, that has the predetermined impedance value while the control signal is enabled or has the high impedance value while the control signal is disabled;

a first receiving unit responsive to one of the receiving signals for generating a first differential signal;

a second receiving unit responsive to the other of the receiving signals for generating a second differential signal; and

a differential amplifier for receiving the first differential signal and the second differential signal and generating the receiving data signal;

wherein the pair of transmitting signals are output from the first terminal and the second terminal, and are determined by the transmitting data signal while the control signal is enabled, otherwise, the pair of transmitting signals are at the high impedance state, and both the third resistor unit and the fourth resistor unit have high impedance values such that the pair of receiving signals are incapable of passing through the third resistor unit and the fourth resistor unit.

14. The interface switching module of claim 13, wherein the first resistor unit and the second resistor unit are transistors having gates receiving the control signal, drains being connected to a voltage source, and sources being defined as the first terminal and the second terminal respectively.

15. The interface switching module of claim 13, wherein the third resistor unit and the fourth resistor unit are transistors having gates receiving the control signal, drains receiving the first receiving signal and the second receiving signal, and sources being connected to ground.

16. The interface switching module of claim 13, wherein the first resistor unit and the second resistor unit both comprise:

a resistor having the predetermined impedance value, wherein one terminal of the resistor is connected to a voltage source; and

a transistor having a gate for receiving the control signal, a drain being connected to the other terminal of the resistor, and a source being defined as the first terminal and the second terminal.

17. The interface switching module of claim 13, wherein the first resistor unit and the second resistor unit both comprise:

a transistor having a gate receiving the control signal and a drain being connected to a voltage source; and

a resistor having the predetermined impedance value, wherein one terminal of the resistor is connected to a source of the transistor, and the other terminal is defined as the first terminal and the second terminal.

18. The interface switching module of claim 13, wherein the third resistor unit and the fourth resistor unit both comprise:

a resistor having the predetermined impedance value, wherein one terminal of the resistor receives the pair of receiving signals, respectively; and

a transistor having a gate receiving the control signal, a drain being connected to the other terminal of the resistor and a source being connected to ground.

19. The interface switching module of claim 13, wherein the third resistor unit and the fourth resistor unit both comprise:

a transistor having a gate receiving the control signal and a drain receiving the pair of receiving signals, respectively; and

a resistor having a resistance value equal to the predetermined impedance value, wherein one terminal of the resistor is connected to a source of the transistor, and the other terminal is connected to ground.

20. The interface switching module of claim 13, wherein the first switch unit and the second switch unit are transistors, the transistors having gates receiving the transmitting data signal and the reverse signal of transmitting data signal, drains being connected to the first resistor unit and the second resistor unit respectively, and sources being connected to a current source.

21. The interface switching module of claim 13, wherein the first receiving unit and the second receiving unit are transistors, the transistors having gates receiving the pair of receiving signals, respectively, drains being connected to a current source, and sources being connected to ground.

22. An interface switching method for a system having an interface switching module that switches between a first serial transmission interface and a second serial transmission interface, the interface switching method comprising:

connecting the system with a first device having the first serial transmission interface;

determining whether a second device having the second serial transmission interface is connected to the system or not;

disconnecting the system from the first device by using an impedance modulating method if the second device is connected to the system, and then returning to the step of determining; and

connecting the system with the first device by using the impedance modulating method if the second device is not connected to the system, and then returning to the step of determining.

23. The interface switching method of claim 22, wherein the impedance modulating method comprises:

using an auto-detection circuit to modulate the equivalent impedances of resistor units of the interface switching module with a high impedance value when disconnecting the system from the first device; and

when connecting the system with the first device, using the auto-detection circuit to modulate the equivalent impedances of all the resistor units of the interface switching module with a predetermined impedance value.

24. The interface switching method of claim 23, wherein each said resistor unit is a transistor, or a resistor cascaded a transistor.