Systems, circuits and methods for dual transformer duplexing
View Patent ↗A circuit for the analog correlation of a signal to remove impairments such as echo, cross talk and intersymbol interference is described. A duplexing circuit which improves echo response by providing a second transformer is described.
1. A duplexing circuit comprising:
a first resistor coupled between a first node and a second node;
a second resistor coupled between the second node and a third node;
a first transformer having a secondary winding coupled to a third resistor, and a primary winding coupled between the third node and a fourth node; and
a second transformer having a secondary winding and a primary winding, the primary winding of the second transformer coupled between the first and fourth nodes,
wherein the duplexing circuit is coupled to a low pass filter through a third transformer, the third transformer being a high frequency transformer.
2. The duplexing circuit of claim 1 , wherein the first transformer and the second transformer are high frequency transformers for coupling frequencies in a gigahertz (GHz) range.
3. The duplexing circuit of claim 1 , wherein the first resistor and the second resistor are 100 ohms.
4. The duplexing circuit of claim 1 , wherein a twisted pair input is coupled to the duplexing circuit through the second transformer.
5. The duplexing circuit of claim 1 , wherein the first transformer is coupled to the third resistor such that the third resistor is not directly connected into the duplexing circuit.
6. A method for improving echo response, comprising:
receiving an input signal from a wire coupled through a first transformer;
modulating the input signal by a second transformer coupled to a resistor for providing an improved echo response for the input signal; and
transmitting the input signal to a low pass filter,
wherein the transmission of the input signal to the low pass filter is through a third transformer, the third transformer being a high frequency transformer.
7. The method of claim 6 , wherein the first transformer and the second transformer are high frequency transformers for coupling frequencies in a gigahertz (GHz) range.
8. The method of claim 6 , wherein the resistor is 100 ohms.
9. The method of claim 6 , wherein the input signal comprises a twisted pair input.
10. The method of claim 6 , wherein the first transformer is coupled to a second resistor.
11. The method of claim 6 , wherein the low pass filter is coupled to an amplifier.
12. A circuit to provide improved echo response, comprising:
a first resistor coupled between a first node and a second node, wherein the first resistor is directly connected into the circuit;
a second resistor directly connected into the circuit and coupled between the second node and a third node;
a first transformer having a secondary winding coupled to a third resistor, and a primary winding coupled between the third node and a fourth node, wherein the third resistor is not directly connected into the circuit; and
a second transformer having a secondary winding and a primary winding, the primary winding of the secondary transformer coupled between the first and fourth nodes,
wherein the circuit is coupled to a low pass filter through a third transformer, the third transformer being a high frequency transformer.
13. The circuit of claim 12 , wherein the first transformer and the second transformer are high frequency transformers for coupling frequencies in a gigahertz (GHz) range.
14. The circuit of claim 12 , wherein a twisted pair input is coupled to the circuit through the second transformer.
15. The circuit of claim 12 , wherein the first transformer is coupled to the third resistor such that the third resistor is not directly connected into the circuit.