Transmitter and receiver of differential current driving mode, and interface system of differential current driving mode including the same

• US 8,324,936 B2
• Filed: 07/07/2009
• Issued: 12/04/2012
• Est. Priority Date: 08/26/2008
• Status: Expired due to Fees

• Current Assignee: Silicon Works Co., Ltd.
• Original Assignee: Silicon Works Co., Ltd.
• Inventors: Kim, Jun Ho, Hong, Ju Pyo, Choi, Jung Hwan, Ryu, Young Soo
• Primary Examiner(s): TRAN, ANH Q
• Application Number:
  US13/059,021
• Publication Number:
  US 20110304356A1
• Time in Patent Office: 1,246 Days
• Field of Search: 326/30, 326/83, 326/86, 326/90, 327/108, 327/112
• US Class Current: 326/86
• CPC Class Codes: H03K 19/0175 Coupling arrangements; Interface arrangements interface arrangements for digital computers G06F3/00, G06F13/00

Abstract

Differential current driving type transmitter and receiver, and an interface system having the transmitter and receiver. The transmitter includes a current source, a current direction selecting block, and a balancing switch block. The current source sources currents to a pair of transmission lines or sinks currents flowing through the pair of transmission lines. The current direction selecting block transfers a current flowing from the current source to one transmission line of the pair of transmission lines and a current flowing through the other transmission line of the pair of transmission lines to the current source. The balancing switch block initializes the pair of transmission lines to a balanced state.

Claims

1. A differential current driving type transmitter comprising:

a current source configured to source currents to a pair of transmission lines and sink currents flowing through the pair of transmission lines;

a current direction selecting block configured to transfer a current flowing from the current source to a first transmission line of the pair of transmission lines and a current flowing through a second transmission line of the pair of transmission lines to the current source;

a balancing switch block configured to initialize the pair of transmission lines to a balanced state,

wherein the current source comprises a current supply source which has one terminal connected to a first voltage and the other terminal connected to a first terminal of the current direction selecting block, and a current sink which has one terminal connected to a second voltage and the other terminal connected to a second terminal of the current direction selecting block,

wherein the balancing switch block comprises a balancing switch which has one terminal connected to the first transmission line and the other terminal connected to the second transmission line and a resistor component which is disposed between the second transmission line and the balancing switch, a value of the resistor component capable of being changed, and

wherein the transmitter further comprises a pre-emphasis circuit comprising;

a second current supply source connected to the first voltage, a third current supply source connected to the first voltage, a second current sink connected to the second voltage, a third current sink connected to the second voltage, a sixth switch, a seventh switch, an eighth switch, and a ninth switch,

wherein the sixth switch and the eighth switch are connected to the first transmission line, and wherein the sixth switch and the eighth switch are positioned on the same line between the second current supply source and the second current sink,

wherein the seventh switch and the ninth switch are connected to the second transmission line, and wherein the seventh switch and the ninth switch are positioned on the same line between the third current supply source and the third current sink, and

wherein the sixth switch and the ninth switch, or the seventh switch and the eighth switch, can be simultaneously opened to increase a data transmission speed of the transmitter.

2. The transmitter according to claim 1, wherein the current direction selecting block comprises:

a first selection switch having one terminal which is connected to the first terminal and the other terminal which is connected to the second transmission line;

a second selection switch having one terminal which is connected to the second terminal and the other terminal which is connected to the first transmission line;

a third selection switch having one terminal which is connected to the first terminal and the other terminal which is connected to the first transmission line; and

a fourth selection switch having one terminal which is connected to the second terminal and the other terminal which is connected to the second transmission line.

3. The transmitter according to claim 2,

wherein a pair of the first selection switch and second selection switch and a pair of the third selection switch and fourth selection switch are simultaneously turned on or off;

and

wherein turn-on and turn-off operations of the pair of the first selection switch and second selection switch are opposite to turn-on and turn-off operations of the pair of the third selection switch and fourth selection switch.

4. The transmitter according to claim 1,

wherein the pre-emphasis circuit is configured to supply or sink currents of predefined magnitudes to the pair of transmission lines before supplying currents from the current source to the pair of transmission lines or sinking currents flowing through the pair of transmission lines.

5. The transmitter according to claim 1,

wherein, when it is necessary to source a current to the first transmission line and sink a current from the second transmission line in the current direction selecting block, the sixth switch is turned on and an initial current is sourced to the first transmission line;

and

wherein, when it is necessary to source a current to the second transmission line and sink a current from the first transmission line in the current direction selecting block, the seventh switch is turned on and an initial current is sourced to the second transmission line.

6. The transmitter according to claim 1,

wherein, when it is necessary to source a current to the first transmission line and sink a current from the second transmission line in the current direction selecting block, the ninth switch is turned on and an initial current is sunk from the second transmission line;

and

wherein, when it is necessary to source a current to the second transmission line and sink a current from the first transmission line in the current direction selecting block, the eighth switch is turned on and an initial current is sunk from the first transmission line.

7. A differential current driving type interface system comprising:

a transmitter configured to adjust directions of currents flowing through two transmission lines depending upon data to be transmitted; and

a receiver connected with the transmitter via the two transmission lines, configured to restore data by sensing the directions of the currents flowing through the two transmission lines, and having a far end resistor having one terminal which is connected to a first transmission line and the other terminal which is connected to a second transmission line and a differential amplification section which amplifies a voltage difference between both terminals of the far end resistor,

wherein the transmitter comprises;

a current source configured to source currents to the two transmission lines and sink currents flowing through the two transmission lines;

a current direction selecting block configured to transfer a current flowing from the current source to a first transmission line of the two transmission lines and a current flowing through a second transmission line of the two transmission lines to the current source;

a balancing switch block configured to initialize the two transmission lines to a balanced state, and having a balancing switch which has one terminal connected to the first transmission line and the other terminal connected to the second transmission line and a resistor component which is disposed between the second transmission line and the balancing switch, a value of the resistor component capable of being changed; and

a pre-emphasis circuit positioned between the balancing switch block of the transmitter and the receiver, the pre-emphasis circuit comprising;

a second current supply source connected to a first voltage, a third current supply source connected to the first voltage, a second current sink connected to a second voltage, a third current sink connected to the second voltage, a sixth switch, a seventh switch, an eighth switch, and a ninth switch,

wherein the sixth switch and the eighth switch are connected to the first transmission line, and wherein the sixth switch and the eighth switch are positioned on the same line between the second current supply source and the second current sink,

wherein the seventh switch and the ninth switch are connected to the second transmission line, and wherein the seventh switch and the ninth switch are positioned on the same line between the third current supply source and the third current sink, and

wherein the sixth switch and the ninth switch, or the seventh switch and the eighth switch, can be simultaneously opened to increase a data transmission speed of the transmitter.

8. The interface system according to claim 7, wherein a direction of a current flowing through one transmission line of the two transmission lines is opposite to a direction of a current flowing through the other transmission line of the two transmission lines.

9. The interface system according to claim 7, wherein magnitudes of the currents flowing through the two transmission lines are the same.

10. The interface system according to claim 7, wherein the receiver comprises the far end resistor which is connected between the two transmission lines, and restores data by amplifying a difference between voltages of both terminals of the far end resistor that drop in correspondence to the currents flowing through the two transmission lines.