Apparatus and Method for interference cancellation in receiver of communication system

• US 20080253489A1
• Filed: 04/10/2008
• Published: 10/16/2008
• Est. Priority Date: 04/16/2007
• Status: Active Grant

• Current Assignee: Realtek Semiconductor Corp.
• Original Assignee: Realtek Semiconductor Corp.
• Inventors: HUANG, Fong Ching
• Granted Patent: US 8,130,879 B2
• Time in Patent Office: Days
• US Class Current: 375/346
• CPC Class Codes: H04B 3/32 Reducing cross-talk, e.g. by compensating

Abstract

An apparatus and method for interference cancellation is provided to cancel the interference such as echo and cross-talk received by a receiver of a communication system. The apparatus includes a digital cancellation signal generator, a first canceller, and a second canceller. The digital cancellation signal generator can generate a digital cancellation signal, which includes a first and a second portion and represents an interference signal within a received signal. The first canceller can perform an analog cancellation on the received signal to output a partially-interference-canceled received signal according to the first portion of the digital cancellation signal. The second canceller can perform a digital cancellation on the partially-interference-canceled received signal according to the second portion of the digital cancellation signal.

Claims

1. An apparatus for interference cancellation used in a receiver of a transceiver of a communication device, the apparatus comprising:

a digital cancellation signal generator for generating a digital cancellation signal comprising a first digital signal and a second digital signal, wherein the digital cancellation signal represents an interference signal within a received signal received by the receiver;

a first canceller, coupled to the digital cancellation signal generator, for performing an analog cancellation on the received signal in an analog domain according to the first digital signal to output a first canceled received signal; and

a second canceller, coupled to the digital cancellation signal generator and the first canceller, for performing a digital cancellation on the first canceled received signal in a digital domain according to the second digital signal to output a digital output signal.

2. The apparatus of claim 1, wherein the interference signal comprises an echo signal, and the digital cancellation signal generator comprises an echo canceller.

3. The apparatus of claim 2, wherein the interference signal further comprises at least one cross-talk signal, and the digital cancellation signal generator further comprises at least one cross-talk canceller.

4. The apparatus of claim 1, wherein the interference signal comprises an echo signal, and a plurality of near-end and far-end cross-talk signals.

5. The apparatus of claim 1, wherein the first digital signal is larger than the second digital signal.

6. The apparatus of claim 1, wherein the first digital signal is at least one most significant bit (MSB) of the digital cancellation signal.

7. The apparatus of claim 6, wherein the first canceller comprises:

a digital-to-analog converter for converting the first digital signal into a first cancellation signal; and

a first adder for subtracting the first cancellation signal from the received signal.

8. The apparatus of claim 7, wherein the first canceller further comprises:

a low pass filter, coupled between the digital-to-analog converter and the first adder, for low pass filtering the first cancellation signal.

9. The apparatus of claim 7, wherein the digital-to-analog converter is a time-interleaved digital-to-analog converter.

10. The apparatus of claim 1, further comprising:

an analog-to-digital converter, coupled to the second canceller, for converting the first canceled received signal outputted by the first canceller into a digital first canceled signal;

wherein the second canceller comprises an adder for subtracting the second digital signal from the digital first canceled signal.

11. The apparatus of claim 10, wherein the analog-to-digital converter is a time-interleaved analog-to-digital converter.

12. The apparatus of claim 10, wherein the first canceller comprises a sample-and-hold circuit and the analog-to-digital converter comprises a quantization circuit.

13. The apparatus of claim 12, wherein the quantization circuit is a time-interleaved quantization circuit.

14. The apparatus of claim 13, wherein the sample-and-hold circuit is a time-interleaved sample-and-hold circuit.

15. The apparatus of claim 1, wherein the communication device comprises a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) circuit for implementing the CSMA/CD function.

16. A method for interference cancellation used in a receiver of a communication system, the method comprising steps of:

receiving a received signal using a hybrid circuit;

in the receiver, generating a digital cancellation signal comprising a first digital signal and a second digital signal, wherein the digital cancellation signal represents an interference signal within the received signal;

in the receiver, converting a first digital signal into a first analog signal;

in the receiver, performing an analog cancellation on the received signal in an analog domain according to the first analog signal to output an analog partially-interference-canceled signal;

in the receiver, converting the analog partially-interference-canceled signal into a digital partially-interference-canceled signal; and

in the receiver, performing a digital cancellation on the digital partially-interference-canceled signal according to the second digital signal to output an digital output signal.

17. The method of claim 16, wherein the digital cancellation signal comprises at least one of an echo cancellation signal and a cross-talk cancellation signal.

18. The method of claim 16, wherein the first digital signal is at least one most significant bit (MSB) of the digital cancellation signal.

19. The method of claim 16, further comprising:

low-pass filtering the first analog signal.

20. The method of claim 16, wherein the step of performing the analog cancellation comprises

sampling the received signal to output a corresponding discrete-time signal;

and

generating the analog partially-interference-canceled signal according to the first analog signal and the discrete-time signal.

21. The method of claim 16, wherein the step of converting the first digital signal is executed by a time-interleaved digital-to-analog converter.

22. The method of claim 16, wherein the step of converting the analog partially-interference-canceled signal is executed by a time-interleaved analog-to-digital converter.