FULL DUPLEX SYSTEM WITH SELF-INTERFERENCE CANCELLATION

• US 20140050124A1
• Filed: 08/14/2012
• Published: 02/20/2014
• Est. Priority Date: 08/14/2012
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Renesas Mobile Corporation (Renesas Electronics Corporation)
• Inventors: Babakhani, Aydin, Yang, Tulong, Chen, Charles
• Granted Patent: US 9,203,455 B2
• Time in Patent Office: Days
• US Class Current: 370/278
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04B 1/18 Input circuits, e.g. for coupling to an antenna or a transmission line coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 1/71072 Successive interference cancellation

Abstract

An apparatus and method enable a full duplex system with self-interference cancellation. Receiving circuitry forming a signal receiving path is arranged for transferring communication signals received via air interface. Transmitting circuitry forming a signal transmission path is arranged for transferring communication signals to be transmitted via air interface. Interference cancellation circuitry is in operable connection between the signal receiving path and the signal transmission path. The receiving circuitry and the transmitting circuitry are arranged to receive and transmit communication signals at the same time and at the same frequency. The interference cancellation circuitry comprises resistance, inductance and capacitance arranged to constitute a center frequency of an isolation range between the signal receiving path and the signal transmission path which substantially falls into the center of a communication band for the signals received and/or to be transmitted via air interface.

Claims

1. An apparatus, comprising:

receiving circuitry forming a signal receiving path arranged for transferring communication signals received via air interface;

transmitting circuitry forming a signal transmission path arranged for transferring communication signals to be transmitted via air interface; and

interference cancellation circuitry in operable connection between the signal receiving path and the signal transmission path,

wherein the receiving circuitry and the transmitting circuitry are arranged to receive and transmit communication signals at the same time and at the same frequency,

wherein the interference cancellation circuitry comprises resistance, inductance and capacitance arranged to constitute a center frequency of an isolation range between the signal receiving path and the signal transmission path which substantially falls into the center of a communication band for the signals received and/or to be transmitted via air interface.

2. The apparatus according to claim 1, further comprising:

an antenna, wherein said same antenna is arranged for both receiving communication signals via air interface and transmitting communication signals via air interface,

wherein the interference cancellation circuitry comprises two inductance elements in an inductance branch, and

wherein the antenna is connected between the two inductance elements in the inductance branch.

3. The apparatus according to claim 2, wherein

the interference cancellation circuitry further comprises a parallel branch having a capacitance element, and a parallel branch having a resistance element.

4. The apparatus according to claim 1, further comprising:

a receiving antenna in operable connection to the signal receiving path and arranged for receiving communication signals via air interface; and

a transmission antenna in operable connection to the signal transmission path and arranged for transmitting communication signals via air interface.

5. The apparatus according to claim 4, wherein

the interference cancellation circuitry comprises a first interference cancellation stage which comprises either one of a first circuit design and a second circuit design, wherein the first circuit design comprises a first parallel branch having an inductance element and a second parallel branch having a capacitance element, and the second circuit design comprises a first parallel branch having an inductance element, a second parallel branch having a capacitance element, and a third parallel branch having a resistance element.

6. The apparatus according to claim 5, wherein

the interference cancellation circuitry additionally comprises a second and a third interference cancellation stage both of the second circuit design and arranged in serial connection with the first interference cancellation stage placed in the middle, and

resonance frequencies of the stages are different from each other.

7. The apparatus according to claim 1, further comprising:

a power amplifier in the signal transmission path and a low noise amplifier in the signal receiving path, wherein the interference cancellation circuitry is connected at the antenna-side between the signal transmission path and the signal receiving path with respect to both the power amplifier and the low noise amplifier.

8. The apparatus according to claim 1, wherein the interference cancellation circuitry consists of fixed elements.

9. The apparatus according to claim 1, wherein the interference cancellation circuitry is formed by a fully passive network.

10. The apparatus according to claim 1, further comprising wired interface circuitry.

11. The apparatus according to claim 1, further comprising:

user interface circuitry; and

user interface software arranged to enable user control through use of a human-machine-interface such as a display.

12. A method, comprising:

receiving communication signals by a receiving circuitry via air interface and transferring the same in a signal receiving path;

transmitting communication signals by a transmitting circuitry via air interface and transferring the same in a signal transmission path,

wherein the communication signals are received and transmitted at the same time and at the same frequency; and

cancelling interference between the signal receiving path and the signal transmission path by interference cancellation circuitry connected there between, which comprises resistance, inductance and capacitance arranged to constitute a center frequency of an isolation range between the signal receiving path and the signal transmission path which substantially falls into the center of a communication band for the signals received and/or transmitted via air interface.

13. The method according to claim 12, further comprising:

connecting two inductance elements in an inductance branch of the interference cancellation circuitry,

connecting an antenna between the two inductance elements in the inductance branch, and

using said same antenna for both receiving communication signals via air interface and transmitting communication signals via air interface.

14. The method according to claim 12, further comprising:

forming a parallel branch having a capacitance element and a parallel branch having a resistance element in the interference cancellation circuitry.

15. The method according to claim 12, further comprising:

connecting a receiving antenna to the signal receiving path and using the same for receiving communication signals via air interface; and

connecting a transmission antenna to the signal transmission path and using the same for transmitting communication signals via air interface.

16. The method according to claim 15, further comprising:

forming the interference cancellation circuitry as a first interference cancellation stage with either one of a first circuit design and a second circuit design, wherein the first circuit design comprises a first parallel branch having an inductance element and a second parallel branch having a capacitance element, and the second circuit design comprises a first parallel branch having an inductance element, a second parallel branch having a capacitance element, and a third parallel branch having a resistance element.

17. The method according to claim 16, further comprising:

additionally forming a second and a third interference cancellation stage both of the second circuit design and serially connecting the second and third interference cancellation stage with the first interference cancellation stage placed in the middle, wherein resonance frequencies of the stages are different from each other.

18. The method according to claim 12, further comprising:

connecting a power amplifier in the signal transmission path and a low noise amplifier in the signal receiving path, wherein the interference cancellation circuitry is connected at the antenna-side between the signal transmission path and the signal receiving path with respect to both the power amplifier and the low noise amplifier.

19. The method according to claim 12, wherein the interference cancellation circuitry consists of fixed elements.

20. The method according to claim 12, wherein the interference cancellation circuitry is formed by a fully passive network.