Multi-band low noise amplifier

1. An apparatus comprising:

a first path tuned to a first frequency band;

a second path tuned to a second frequency band; and

cross-coupled circuitry having a first input coupled to the first path and a second input coupled to the second path and having a first output coupled to the second path and a second output coupled to the first path, wherein the cross-coupled circuitry comprises:

a first set of transistors, a first transistor of the first set of transistors having a gate coupled led to the first path and a second transistor of the first set of transistors having a drain coupled to the second path; and

a second set of transistors, a first transistor of the second set of transistors having a gate coupled to the second path and a second transistor of the second set of transistors having a drain coupled to the first path.

2. The apparatus of claim 1 , wherein the first path, the second path, and the cross-coupled circuitry are included in a low noise amplifier.

3. The apparatus of claim 1 , wherein the first transistor of the first set of transistors and the first transistor of the second set of transistors are common source transistors.

4. The apparatus of claim 1 , wherein the first frequency band is a 2.4 Gigahertz (GHz) frequency band, and wherein the second frequency band is a 5.6 GHz frequency band.

5. The apparatus of claim 1 , further comprising a first inductive-capacitive (LC) circuit coupled to the first path, wherein the first LC circuit resonates at a frequency within the first frequency band.

6. The apparatus of claim 5 , wherein a first inductor of the first LC circuit is included in a first transformer.

7. The apparatus of claim 1 , further comprising a second inductive-capacitive (LC) circuit coupled to the second path, wherein the second LC circuit resonates at a frequency within the second frequency band.

8. The apparatus of claim 7 , wherein a second inductor of the second LC circuit is included in a second transformer.

9. The apparatus of claim 1 , further comprising:

a third path tuned to a third frequency band;

second cross-coupled circuitry having a first input coupled to the second path and a second input coupled to the third path and having a first output coupled to the third path and a second output coupled to the second path; and

third cross-coupled circuitry having a first input coupled to the first path and a second input coupled to the third path and having a first output coupled to the third path and a second output coupled to the first path.

10. The apparatus of claim 9 , wherein the third frequency band is an 800 Megahertz (MHz) frequency band.

11. The apparatus of claim 9 , further comprising a third inductive-capacitive (LC) circuit coupled to the third path, wherein the third LC circuit resonates at a frequency within the third frequency band.

12. The apparatus of claim 1 , wherein the first frequency band and the second frequency band comply with an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard.

13. The apparatus of claim 1 , further comprising:

a transistor having a drain coupled to the first path and coupled to the second path; and

a dual band matching network having an input configured to receive a radiofrequency (RF) signal and an output coupled to a gate of the transistor.

14. The apparatus of claim 1 , further comprising:

a first transistor having a drain coupled to the first path;

a second transistor having a drain coupled to the second path; and

a dual band matching network having an input configured to receive a radiofrequency (RF) signal and an output coupled to a gate of the first transistor and to a gate of the second transistor.

15. The apparatus of claim 1 , wherein the first transistor of the first set of transistors is configured to receive a signal and to phase shift the signal by approximately 180 degrees.

16. An apparatus comprising:

means for amplifying first signal components, wherein the means for amplifying the first signal components is tuned to a first frequency band;

means for amplifying second signal components, wherein the means for amplifying the second signal components is tuned to a second frequency band; and

means for generating one or more cancellation signals having a first input coupled to the means for amplifying the first signal components and a second input coupled to the means for amplifying the second signal components and having a first output coupled to the means for amplifying the second signal components and a second output coupled to the means for amplifying the first signal components, the means for generating comprising:

first means for amplifying signals having a gate coupled to the means for amplifying the first signal components and second means for amplifying signals having a drain coupled to the means for amplifying the second signal components; and

third means for amplifying signals having a gate coupled to the means for amplifying the second signal components and fourth means for amplifying signals having a drain coupled to the means for amplifying the first signal components.

17. The apparatus of claim 16 , wherein the means for amplifying the first signal components, the means for amplifying the second signal components, and the means for generating one or more cancellation signals are included in a low noise amplifier.

18. The apparatus of claim 16 , wherein the first frequency band is a 2.4 Gigahertz (GHz) frequency band, and wherein the second frequency band is a 5.6 GHz frequency band.

19. A method comprising:

amplifying first signal components at a first path tuned to a first frequency band;

amplifying second signal components at a second path tuned to a second frequency band; and

generating one or more cancellation signals at cross-coupled circuitry having a first input coupled to the first path and a second input coupled to the second path and having a first output coupled to the second path and a second output coupled to the first path, wherein the cross-coupled circuitry comprises:

a first set of transistors, a first transistor of the first set of transistors having a gate coupled to the first path and a second transistor of the first set of transistors having a drain coupled to the second path; and

a second set of transistors, a first transistor of the second set of transistors having a gate coupled to the second path and a second transistor of the second set of transistors having a drain coupled to the first path.

20. The method of claim 19 , wherein the first frequency band is a 2.4 Gigahertz (GHz) frequency band, and wherein the second frequency band is a 5.6 GHz frequency band.