Frequency agile duplex filter
View Patent ↗Systems and methods are disclosed for an electronically adjustable signal filter system, which comprises, in some embodiments, a first filter coupled to an antenna coupling network and a second filter, a power amplifier coupled to the first filter, an antenna connected to an antenna coupling network, a pilot tone generator coupled to the first filter, and a first signal source connected to the power amplifier and first filter. In some embodiments, the power amplifier amplifies the first signal, the first filter places a notch into the first signal transmitted to the antenna coupling network, the antenna coupling network combines the first signal and a second signal received from the antenna and transmits a third signal to the second filter.
1. A method of processing signals in a wireless communication equipment, the method comprising:
notch filtering an input transmit signal to reduce signal power in at least one receive frequency band to provide a filtered transmit signal, wherein notch filtering the input transmit signal comprises tuning a reject band of notch filtering based on a pilot signal; and
coupling the filtered transmit signal to an antenna via an antenna coupling network for transmission by the antenna.
2. A method as defined in claim 1 , wherein the step of notch filtering the input transmit signal comprises:
amplifying the input transmit signal to provide an amplified transmit signal; and
notch filtering the amplified transmit signal to provide the filtered transmit signal.
3. A method as defined in claim 2 , wherein the step of notch filtering the input transmit signal comprises using vector cancellation to suppress receive band noise.
4. A method as defined in claim 3 , further comprising isolating the vector cancellation from the input transmit signal.
5. A method as defined in claim 1 , further comprising:
coupling a receive signal from the antenna to the antenna coupling network; and
notch filtering the receive signal to reduce power in a transmit frequency band to provide a filtered receive signal.
6. A method as defined in claim 5 , wherein notch filtering the receive signal comprises:
selecting a transmit frequency band from a plurality of transmit frequency bands; and
notch filtering the receive signal to reduce power in the selected frequency band to provide the filtered receive signal.
7. A method as defined in claim 1 , wherein the step of notch filtering the input transmit signal comprises reducing signal power in multiple receive frequency bands.
8. A method as defined in claim 5 , further comprising amplifying the filtered receive signal with a low noise amplifier to provide an amplified receive signal.
9. A method as defined in claim 8 , further comprising down converting the amplified receive signal to provide a down-converted receive signal.
10. A method as defined in claim 1 , wherein the antenna coupling network comprises at least one circulator operable:
to couple the filtered transmit signal from a transmit signal path to the antenna for transmission by the antenna; and
to couple a receive signal from the antenna to a receive signal path.
11. A method as defined in claim 10 , further comprising:
estimating a portion of the filtered transmit signal coupled to the receive signal path by the at least one circulator; and
at least partially cancelling a portion of the filtered transmit signal coupled to the receive signal path.
12. An electronically adjustable signal filter system comprising:
an antenna coupling network; and
a filter coupled to the antenna coupling network, the filter configured to:
notch filter an input transmit signal to reduce signal power in at least one receive frequency band to provide a filtered transmit signal, wherein notch filtering the input transmit signal comprises tuning a reject band of notch filtering based on a pilot signal; and
couple the filtered transmit signal to an antenna via the antenna coupling network for transmission by the antenna.
13. The filter system of claim 12 , further comprising a power amplifier coupled to the filer, wherein the filter is configured to notch filter the input transmit signal by:
amplifying the input transmit signal to provide an amplified transmit signal; and
notch filtering the amplified transmit signal to provide the filtered transmit signal.
14. The filter system of claim 13 , wherein the filter is configured to notch filter the input transmit signal by using vector cancellation to suppress receive band noise.
15. The filter system of claim 14 , wherein the filter system is configured to isolate the vector cancellation from the input transmit signal.
16. The filter system of claim 12 , wherein the filter system is configured to couple a receive signal from the antenna to the antenna coupling network; and the filter is configured to notch filter the receive signal to reduce power in a transmit frequency band to provide a filtered receive signal.
17. The filter system of claim 16 , wherein the filter is configured to notch filter the receive signal by:
selecting a transmit frequency band from a plurality of transmit frequency bands; and
notch filtering the receive signal to reduce power in the selected frequency band to provide the filtered receive signal.
18. The filter system of claim 12 , wherein the filter is configured to notch filter the input transmit signal by reducing signal power in multiple receive frequency bands.
19. The filter system of claim 12 , further comprising an amplifier configured to amplify the filtered receive signal to provide an amplified receive signal.
20. The filter system of claim 19 , further comprising a down conversion mixer configured to down convert the amplified receive signal to provide a down-converted receive signal.
21. The filter system of claim 12 , wherein the antenna coupling network comprises at least one circulator operable:
to couple the filtered transmit signal from a transmit signal path to the antenna for transmission by the antenna; and
to couple a receive signal from the antenna to a receive signal path.
22. The filter system of claim 21 , wherein the at least one circulator is further operable to:
estimate a portion of the filtered transmit signal coupled to the receive signal path; and
at least partially cancel a portion of the filtered transmit signal coupled to the receive signal path.