Joint transmit/receive image compensation with blind adaptive calibration in a transceiver system
Joint transmit/receive image compensation is performed with the transceiver online and on an ongoing basis by using blind image compensation techniques when in a receive mode in order to converge receive image compensation coefficients based on “live” receive data and then in a transmit mode, after convergence of the receive image compensation coefficients, coupling the “live” transmit signal to the receive signal path to adapt the transmit image compensation coefficients.
1. A joint transmit/receive image compensation system comprising:
a transmit signal path comprising a transmitter for generating transmit signals to a transmit interface and a transmit image compensation filter for filtering images from the transmit signals;
a receive signal path comprising a blind adaptive calibration circuit for joint transmit/receive image compensation and a receive image compensation filter for filtering images from receive signals;
a switching circuit for selectively switching the receive signal path between a receive interface and the transmit signal path; and
a calibration controller in communication with the switching circuit and configured to run:
(a) an online receive calibration mode in which the switching circuit couples the receive signal path to the receive interface so that the blind adaptive calibration circuit receives signals from the receive interface and adapts receive image compensation coefficients for the receive image compensation filter based on the signals from the receive interface; and
(b) an online transmit calibration mode in which, after convergence of the receive image compensation coefficients, the switching circuit couples the receive signal path to the transmit signal path so that the blind adaptive calibration circuit receives the transmit signals from the transmit signal path and adapts transmit image compensation coefficients for the transmit image compensation filter based on the transmit signals from the transmit signal path.
2. A system according to claim 1 , wherein the calibration controller is configured to run an initial offline receive calibration mode in which the switching circuit couples the receive signal path to the transmit signal path so that the blind adaptive calibration circuit receives the transmit signals from the transmit signal path and adapts at least receive image compensation coefficients for the receive image compensation filter based on the transmit signals from the transmit signal path.
3. A system according to claim 2 , wherein the blind adaptive calibration circuit also adapts transmit image compensation coefficients for the transmit image compensation filter in the initial offline receive calibration mode.
4. A system according to claim 1 , wherein, in the online transmit calibration mode, the transmit signals from the transmit path are provided to the blind adaptive calibration circuit through a 0 degree path.
5. A system according to claim 1 , wherein, in the online transmit calibration mode, the transmit signals from the transmit path are provided to the blind adaptive calibration circuit through a 90 degree path.
6. A system according to claim 1 , wherein the transmit and receive signal paths use direct conversion.
7. A system according to claim 1 , wherein the transmit and receive signal paths convert between IF and I/Q.
8. A system according to claim 1 , wherein the calibration controller is configured to repeat the online receive calibration mode when the system is in a subsequent online receive mode and to repeat the online transmit calibration mode when the system is in a subsequent online transmit mode such that the online calibration mode is switched as the online transmit/receive mode switches.
9. A joint transmit/receive image compensation method in a transceiver having a transmit signal path comprising a transmitter for generating transmit signals to a transmit interface and a transmit image compensation filter for filtering images from the transmit signals, a receive signal path comprising a blind adaptive calibration circuit for joint transmit/receive image compensation and a receive image compensation filter for filtering images from receive signals, and a switching circuit for selectively switching the receive signal path between a receive interface and the transmit signal path, the method comprising:
in an online receive calibration mode, coupling, via the switching circuit, the receive signal path to the receive interface so that the blind adaptive calibration circuit receives signals from the receive interface and adapting, by the blind adaptive calibration circuit, receive image compensation coefficients for the receive image compensation filter based on the signals from the receive interface; and
in an online transmit calibration mode, after convergence of the receive image compensation coefficients, coupling, via the switching circuit, the receive signal path to the transmit signal path so that the blind adaptive calibration circuit receives the transmit signals from the transmit signal path and adapting, by the blind adaptive calibration circuit, transmit image compensation coefficients for the transmit image compensation filter based on the transmit signals from the transmit signal path.
10. A method according to claim 9 , further comprising:
in an initial offline receive calibration mode, coupling, via the switching circuit, the receive signal path to the transmit signal path so that the blind adaptive calibration circuit receives the transmit signals from the transmit signal path and adapting, by the blind adaptive calibration circuit, at least receive image compensation coefficients for the receive image compensation filter based on the transmit signals from the transmit signal path.
11. A method according to claim 10 , further comprising:
adapting transmit image compensation coefficients for the transmit image compensation filter by the blind adaptive calibration circuit in the initial offline receive calibration mode.
12. A method according to claim 9 , further comprising:
repeating the online receive calibration mode when the system is in a subsequent online receive mode; and
repeating the online transmit calibration mode when the system is in a subsequent online transmit mode such that the online calibration mode is switched as the online transmit/receive mode switches.
13. An RF integrated circuit (RFIC) including a joint transmit/receive image compensation system, the RFIC comprising:
a transmit signal path comprising a transmitter for generating transmit signals to a transmit interface and a transmit image compensation filter for filtering images from the transmit signals;
a receive signal path comprising a blind adaptive calibration circuit for joint transmit/receive image compensation and a receive image compensation filter for filtering images from receive signals;
a switching circuit for selectively switching the receive signal path between a receive interface and the transmit signal path; and
a calibration controller in communication with the switching circuit and configured to run:
(a) an online receive calibration mode in which the switching circuit couples the receive signal path to the receive interface so that the blind adaptive calibration circuit receives signals from the receive interface and adapts receive image compensation coefficients for the receive image compensation filter based on the signals from the receive interface; and
(b) an online transmit calibration mode in which, after convergence of the receive image compensation coefficients, the switching circuit couples the receive signal path to the transmit signal path so that the blind adaptive calibration circuit receives the transmit signals from the transmit signal path and adapts transmit image compensation coefficients for the transmit image compensation filter based on the transmit signals from the transmit signal path.
14. An RFIC according to claim 13 , wherein the RFIC includes a common arm and an element RF arm, and wherein the transmit image compensation filter, the receive image compensation filter, the switching circuit, and the blind adaptive calibration circuit are configured in the common arm.
15. An RFIC according to claim 13 , wherein the RFIC includes a common arm and an element RF arm, and wherein the transmit image compensation filter, the receive image compensation filter, the switching circuit, and the blind adaptive calibration circuit are configured in the element RF arm.
16. An RFIC according to claim 13 , wherein the calibration controller is configured to run an initial offline receive calibration mode in which the switching circuit couples the receive signal path to the transmit signal path so that the blind adaptive calibration circuit receives the transmit signals from the transmit signal path and adapts at least receive image compensation coefficients for the receive image compensation filter based on the transmit signals from the transmit signal path.
17. An RFIC according to claim 16 , wherein the blind adaptive calibration circuit also adapts transmit image compensation coefficients for the transmit image compensation filter in the initial offline receive calibration mode.
18. An RFIC according to claim 13 , wherein, in the online transmit calibration mode, the transmit signals from the transmit path are provided to the blind adaptive calibration circuit through a 0 degree path.
19. An RFIC according to claim 13 , wherein, in the online transmit calibration mode, the transmit signals from the transmit path are provided to the blind adaptive calibration circuit through a 90 degree path.
20. An RFIC according to claim 13 , wherein the transmit and receive signal paths use direct conversion.
21. An RFIC according to claim 13 , wherein the transmit and receive signal paths convert between IF and I/Q.
22. An RFIC according to claim 13 , wherein the calibration controller is configured to repeat the online receive calibration mode when the system is in a subsequent online receive mode and to repeat the online transmit calibration mode when the system is in a subsequent online transmit mode such that the online calibration mode is switched as the online transmit/receive mode switches.