Current-efficient low noise amplifier (LNA)

1. A device, comprising:

a multi-mode low noise amplifier (LNA) having a first amplifier stage and having a single-carrier mode and a carrier aggregation (CA) mode; and

a second amplifier stage coupled to the first amplifier stage, the second amplifier stage having a plurality of amplification paths configured to amplify a plurality of carrier frequencies of a carrier-aggregated communication channel and provide a corresponding plurality of output signals at an LNA output when the first amplifier stage is in the CA mode, the first amplifier stage configured to bypass the second amplifier stage to provide another output signal at the LNA output when the first amplifier stage is in the single-carrier mode.

2. The device of claim 1 , wherein the first amplifier stage is configured to generate a current output when the first amplifier stage is in the single-carrier mode.

3. The device of claim 1 , further comprising a resonator circuit configured to receive a current output of the first amplifier stage, the resonator circuit configured to convert the current output to a voltage output, the voltage output provided to the plurality of amplification paths in the second amplifier stage.

4. The device of claim 1 , wherein the plurality of amplification paths in the second amplifier stage comprise a plurality of adjustable gain stages.

5. The device of claim 4 , wherein at least one of the plurality of adjustable gain stages comprises an adjustable input capacitance.

6. The device of claim 5 , wherein the adjustable input capacitance is configured to change an input impedance of the plurality of adjustable gain stages.

7. The device of claim 1 , further comprising a plurality of first amplifier stages coupled to one second amplifier stage.

8. A method comprising:

setting a mode of a multi-mode low noise amplifier (LNA) to a state indicating one of a single-carrier mode and a carrier aggregation (CA) mode;

amplifying a communication signal in a first amplifier stage of the multi-mode LNA;

amplifying a plurality of carrier frequencies of the communication signal using a plurality of amplifier paths of a second amplifier stage coupled to the first amplifier stage, and providing a corresponding plurality of output signals at an LNA output when the LNA is set to the CA mode; and

bypassing the second amplifier stage by the first amplifier stage providing another output signal to the LNA output when the LNA is set to the single-carrier mode.

9. The method of claim 8 , wherein:

bypassing the second amplifier stage comprises generating a current in the first amplifier stage when the communication signal comprises a single carrier in the single-carrier mode.

10. The method of claim 8 , further comprising:

generating a current output of the first amplifier stage;

converting the current output to a voltage output; and

amplifying the voltage output in the plurality of amplifier paths in the second amplifier stage.

11. A device, comprising:

means for amplifying a communication signal in a multi-stage low noise amplifier configurable to amplify the communication signal having a first carrier in a first amplifier stage;

means for amplifying the communication signal having a second carrier in the first amplifier stage and a second amplifier stage;

means for amplifying a corresponding plurality of carrier frequencies in a carrier aggregation mode; and

means for bypassing the second amplifier stage when the communication signal comprises a single carrier.

12. The device of claim 11 , further comprising:

means for generating a current output of the first amplifier stage;

means for converting the current output to a voltage output; and

means for amplifying the voltage output in a plurality of amplifier paths in the second amplifier stage.

13. The device of claim 11 , further comprising means for adjusting a gain in each of the plurality of amplification paths in the second amplifier stage.

14. The device of claim 13 , further comprising means for adjusting a capacitance at an input of at least one of the plurality of adjustable gain stages.

15. The device of claim 14 , wherein the means for adjusting a capacitance at an input of at least one of the plurality of adjustable gain stages comprises means for changing an input impedance of the plurality of adjustable gain stages.

16. The device of claim 11 , further comprising means for coupling a plurality of first amplifier stages to one second amplifier stage.