Front end module with tone injection

1. A radio front end comprising:

a power amplifier configured to amplify an up-converted signal to produce an outbound wireless signal;

tone injection circuitry configured, in a first mode, to produce a tone having a frequency that is substantially similar to a carrier frequency of an inbound wireless signal;

a duplexer coupled to an antenna, the power amplifier, and the tone injection circuitry, and configured to:

in the first mode, provide electrical isolation between the outbound wireless signal and a combination signal of the tone and inbound wireless signal; and

in a second mode, provide electrical isolation between the outbound wireless signal and the inbound wireless signal;

a balancing network coupled to the duplexer and configured to have an impedance that substantially matches an impedance of the antenna;

a processor configured in the first mode to:

determine an amplitude of a tone component of the combination signal;

correlate the amplitude of the tone component to an inbound frequency band isolation; and

adjust baseband processing of a down converted representation of the combination signal based on the inbound frequency band isolation.

2. The radio front end of claim 1 , wherein the processor is further configured to:

enable the first mode when noise of the inbound wireless signal compares favorably to a noise threshold; and

enable the second mode when the noise of the inbound wireless signal compares unfavorably to the noise threshold, wherein the tone injection circuitry is disabled in the second mode.

3. The radio front end of claim 1 further comprising:

a low noise amplifier configured to amplify the combination signal to produce an amplified combination signal; and

a down-conversion module configured to convert the amplified combination signal into a baseband or near-baseband signal.

4. The radio front end of claim 3 , wherein the processor is further configured to adjust baseband processing of the down converted representation of the combination signal by:

determining a down-converted tone component from the down converted representation of the combination signal;

determining a transmit noise based on the down-converted tone component; and

adjusting a down-converted inbound signal component of the down converted representation of the combination signal based on the transmit noise.

5. The radio front end of claim 1 , wherein the processor is further operation to:

generate a tuning signal based on electrical performance characteristics of the duplexer;

send the tuning signal to the balancing network that adjusts the impedance based on the tuning signal; and

adjust the tuning signal based on inbound frequency band isolation.

6. The radio front end of claim 1 , further comprising:

a front end module that includes the power amplifier, the tone injection circuitry, the duplexer, and the tunable balancing network; and

a system on a chip module that includes the processor.

7. The radio front end of claim 1 , wherein the outbound wireless signal is formed according to at least one of a cellular communication standard and a Wireless Local Area Network communication standard.

8. The radio front end of claim 1 , wherein the processor comprises a baseband processor.

9. The radio front end of claim 1 , wherein the processor comprises an application specific integrated circuit.

10. A radio front end comprising:

a power amplifier configured to amplify an up-converted signal to produce an outbound wireless signal;

tone injection circuitry configured to produce a tone having a frequency that is substantially similar to a carrier frequency of an inbound wireless signal;

a duplexer coupled to an antenna, the power amplifier, and the tone injection circuitry and that is configured to provide electrical isolation between the outbound wireless signal and a combination signal of the tone and the inbound wireless signal;

a balancing network configured to establish an impedance that substantially matches an impedance of the antenna based on a tuning signal;

a low noise amplifier configured to amplify the combination signal to produce an amplified combination signal;

a down conversion module configured to convert the amplified combination signal into a baseband or near-baseband signal; and

a processor configured in the first mode to:

generate the tuning signal based on an electrical performance characteristic of the duplexer;

convert the baseband or near-baseband signal into a baseband tone signal and a baseband inbound signal;

determine an inbound frequency band isolation based on the baseband tone signal; and

adjust the tuning signal based on the inbound frequency band isolation.

11. The radio front end of claim 10 , wherein the processor is further configured to adjust the baseband inbound signal based on the inbound frequency band isolation to compensate for transmit noise in an inbound frequency band.

12. The radio front end of claim 10 , further comprising:

a front end module that includes the power amplifier, the tone injection circuitry, the duplexer, and the tunable balancing network; and

a system on a chip module that includes the processor, the low noise amplifier, and the down conversion module.

13. The radio front end of claim 10 , wherein the processor is further configured to:

enable a first mode when noise of the inbound wireless signal compares favorably to a noise threshold; and

enable a second mode when the noise of the inbound wireless signal compares unfavorably to the noise threshold, wherein the tone injection circuitry is enabled to generate the tone in the first mode and is disabled in the second mode.

14. The radio front end of claim 10 , wherein the outbound wireless signal is formed according to at least one of a cellular communication standard and a Wireless Local Area Network communication standard.

15. The radio front end of claim 10 , wherein the processor comprises a baseband processor.

16. The radio front end of claim 10 , wherein the processor comprises an application specific integrated circuit.

17. A system on a chip comprising:

a low noise amplifier configured to amplify a combination signal to produce an amplified combination signal, wherein the combination signal is a combination of a tone and an inbound wireless signal received from a duplexer;

a down conversion module configured to convert the amplified combination signal into a baseband or near-baseband signal; and

a processor configured in a first mode to:

generate a tuning signal based on an electrical performance characteristic of the duplexer;

convert the baseband or near-baseband signal into a baseband tone signal and a baseband inbound signal;

determine an inbound frequency band isolation based on the baseband tone signal; and

adjust the tuning signal based on the inbound frequency band isolation.

18. The system on a chip of claim 17 , wherein the processor is further configured to adjust the baseband inbound signal based on the inbound frequency band isolation to compensate for transmit noise in an inbound frequency band.

19. The system on a chip of claim 17 , wherein the processor is further configured to:

enable a first mode when noise of the inbound wireless signal compares favorably to a noise threshold; and

enable a second mode when the noise of the inbound wireless signal compares unfavorably to the noise threshold, wherein the tone injection circuitry is enabled to generate the tone in the first mode and is disabled in the second mode.

20. The system on a chip of claim 17 , wherein the processor comprises a baseband processor.