Passive equalizer capable of use in high-speed data communication

1. A passive equalizer comprising:

a first resistive element coupled between an input node and an output node;

a first inductive element and a second resistive element coupled in series between the output node and a first voltage supply node;

a first variable capacitor coupled between the input node and a first node located between the first inductive element and the second resistive element;

a second inductive element and a third resistive element coupled in series between the input node and a second voltage supply node, the first voltage supply node configured to supply a first voltage different from a second voltage supplied at the second voltage supply node; and

a first capacitive element coupled between the output node and a second node located between the second inductive element and the third resistive element.

2. The passive equalizer of claim 1 , wherein a first terminal of the second inductive element is coupled to the input node, a second terminal of the second inductive element is coupled to a first terminal of the third resistive element, and a second terminal of the third resistive element is coupled to the second voltage supply node.

3. The passive equalizer of claim 1 , wherein the first voltage supply node supplies a reference voltage and the second voltage supply node supplies a ground voltage.

4. The passive equalizer of claim 1 , further comprising:

an active equalizer, an input of the active equalizer coupled to the output node.

5. The passive equalizer of claim 1 , further comprising:

an active equalizer stage, an output of the active equalizer coupled to the input node.

6. The passive equalizer of claim 1 , wherein a first terminal of the first inductive element is coupled to the output node, a second terminal of the first inductive element is coupled to a first terminal of the second resistive element, and a second terminal of the second resistive element is coupled to the first voltage supply node.

7. The passive equalizer of claim 6 , wherein the first voltage supply node supplies a reference voltage.

8. The passive equalizer of claim 6 , wherein the second resistive element is a variable resistor.

9. The passive equalizer of claim 8 , wherein the first voltage supply node is characterized as ground.

10. A passive equalizer comprising:

a first input node;

a first output node;

a first resistive element coupled between the first input node and the first output node;

a first inductive element having a first terminal coupled to the first output node;

a first variable capacitor having a first terminal coupled to the first input node and a second terminal coupled to a second terminal of the first inductive element;

a first variable resistor having a first terminal coupled to a second terminal of the first inductive element and to the second terminal of the first variable capacitor, and a second terminal coupled to a first voltage supply node

a second resistive element coupled between a second input node and a second output node;

a second inductive element having a first terminal coupled to the second output node;

a second variable capacitor having a first terminal coupled to the second input node and a second terminal coupled to a second terminal of the second inductive element; and

a second variable resistor having a first terminal coupled to a second terminal of the second inductive element and to the second terminal of the second variable capacitor, and a second terminal coupled to the first voltage supply node;

wherein the first input node is configured to receive a first signal and the second input node is configured to receive a second signal, the second signal being a complementary signal of the first signal.

11. The passive equalizer of claim 10 , further comprising:

an active equalizer, wherein a first input of the active equalizer is coupled to the first output node and a second input of the active equalizer is coupled to the second output node.

12. The passive equalizer of claim 10 , further comprising:

an active equalizer stage, wherein a first output of the active equalizer stage is coupled to the first input node and a second output of the active equalizer stage is coupled to the second input node.

13. The passive equalizer of claim 10 , further comprising:

a third inductive element having a first terminal coupled to the first input node;

a first capacitive element having a first terminal coupled to the first output node and a second terminal coupled to a second terminal of the third inductive element; and

a third resistive element having a first terminal coupled to a second terminal of the third inductive element and to the second terminal of the first capacitive element, and a second terminal coupled to the first voltage supply node.

14. The passive equalizer of claim 13 , wherein the first voltage supply node is characterized as a ground node.

15. A receiver, comprising:

an active equalizer; and

a passive equalizer coupled to the active equalizer, the passive equalizer including:

a first resistive element coupled between an input node and an output node;

a first inductive element having a first terminal coupled to the output node;

a first variable capacitor having a first terminal coupled to the input node and a second terminal coupled to a second terminal of the first inductive element;

a second resistive element having a first terminal coupled to a second terminal of the first inductive element and to the second terminal of the first variable capacitor, and a second terminal coupled to a first voltage supply node, the first voltage supply node configured to supply a reference voltage;

a second inductive element and a third resistive element coupled in series between the input node and a second voltage supply node, the second voltage supply node configured to supply a voltage different from the reference voltage; and

a first capacitive element coupled between the output node and a second node located between the second inductive element and the third resistive element.

16. The receiver of claim 15 , wherein an output of the active equalizer is coupled to the input node of the passive equalizer.

17. The receiver of claim 15 , wherein the first output node of the passive equalizer is coupled to an input of the active equalizer.

18. The receiver of claim 15 , wherein a first terminal of the first inductive element is coupled to the output node, a second terminal of the first inductive element is coupled to a first terminal of the second resistive element, and a second terminal of the second resistive element is coupled to the first voltage supply node.

19. The receiver of claim 15 , wherein a first terminal of the second inductive element is coupled to the input node, a second terminal of the second inductive element is coupled to a first terminal of the third resistive element, and a second terminal of the third resistive element is coupled to the second voltage supply node.

20. The receiver of claim 15 , further comprises:

a fourth resistive element coupled between a second input node and a second output node;

a third inductive element having a first terminal coupled to the second output node;

a second variable capacitor having a first terminal coupled to the second input node and a second terminal coupled to a second terminal of the third inductive element; and

a fifth resistive element having a first terminal coupled to a second terminal of the third inductive element and to the second terminal of the second variable capacitor, and a second terminal coupled to a third voltage supply node;

wherein the input node is configured to receive a first signal and the second input node is configured to receive a second signal, the second signal being a complementary signal of the first signal.