Systems and methods for generating calibration data in active antenna modules having antenna-side filter arrays therein
A system for generating calibration data in an active antenna system (AAS) radio includes an array of directional couplers within a multi-channel transmit/receive signal path of the AAS radio, and a combiner network electrically coupled to the array of directional couplers. An array of filters is provided within the multi-channel transmit/receive signal path. The array of filters is electrically coupled to antenna-side terminals of the array of directional couplers. A plurality of pairs of transmitters and receivers are provided, which include a transmitter and a receiver that operate as a reference transmitter and a reference receiver, respectively. A removable routing network is provided, which is electrically coupled to antenna-side terminals of the array of filters, and is configured to feed back factory calibration signals (generated by the AAS radio during factory calibration) to antenna-side terminals of the array of filters. A multi-stage switch network is provided, which is electrically coupled to the reference transmitter, the reference receiver, the combiner network, and a factory calibration port of the routing network.
1. A method of generating calibration data in an active antenna system (AAS) radio, comprising:
transmitting first calibration signals through a plurality of first calibration loops, which include respective filters within a multi-channel transmit/receive signal path of the AAS radio; and
transmitting second calibration signals through a plurality of second calibration loops, which include respective in-line directional couplers and respective portions of a combiner network on a transmit side of the filters within the AAS radio,
wherein the first calibration signal and the second calibration signal both pass through a first of the in-line directional couplers.
2. The method of claim 1 , further comprising:
transmitting third calibration signals through a plurality of third calibration loops, which include respective ones of the in-line directional couplers and respective portions of the combiner network on the transmit side of the filters, and terminate at a reference receiver within the AAS radio.
3. The method of claim 2 , wherein the first calibration signals and the second calibration signals are transmitted through the first and second pluralities of calibration loops by a reference transmitter within the AAS radio.
4. The method of claim 3 , wherein the third calibration signals are transmitted through the plurality of third calibration loops by respective ones of a corresponding plurality of transmitters within the AAS radio.
5. The method of claim 4 , wherein the AAS radio comprises a multi-stage switch network electrically coupled to the reference transmitter and the reference receiver.
6. The method of claim 5 , wherein each of the first, second and third calibration loops pass through respective portions of the multi-stage switch network.
7. The method of claim 6 , wherein a 1:2 N routing network is electrically coupled to the multi-stage switch network during said transmitting first calibration signals through the plurality of first calibration loops, where N is a positive integer greater than two.
8. The method of claim 7 , wherein the 1:2 N routing network is electrically coupled to antenna-side terminals of the filters during said transmitting first calibration signals through the plurality of first calibration loops.
9. The method of claim 3 , wherein an antenna is electrically coupled to the multi-channel transmit/receive signal path of the AAS radio during said transmitting third calibration signals through the plurality of third calibration loops, but not during said transmitting first and second calibration signals through the plurality of first calibration loops and the plurality of second calibration loops, respectively.
10. A method of operating an active antenna system (AAS), comprising:
generating factory calibration data using a removable routing network, which feeds back factory calibration signals to antenna-side terminals of a filter array within a multi-channel transmit/receive signal path of the AAS radio; then
removing the routing network from the antenna-side terminals of the filter array; then
attaching an antenna to the multi-channel transmit/receive signal path of the AAS; and then
generating field calibration data for the AAS.
11. The method of claim 10 , wherein the removable routing network is a 1:2 N routing network having an input port electrically couped to a factory calibration port of the AAS radio, where N is a positive integer greater than two.
12. The method of claim 10 , wherein generating factory calibration data comprises:
transmitting first calibration signals through each of a plurality of first calibration loops, which include respective portions of the removable routing network; and
transmitting second calibration signals through each of a plurality of second calibration loops, which include respective in-line directional couplers and respective portions of a combiner network on a transmit side of the filter array within the AAS.
13. The method of claim 12 , wherein generating field calibration data comprises transmitting third calibration signals through each of a plurality of third calibration loops, which include respective ones of the in-line directional couplers and respective portions of the combiner network on the transmit side of the filter array, and terminate at a reference receiver within the AAS.
14. The method of claim 13 , wherein the first calibration signals and the second calibration signals are transmitted by a reference transmitter within the AAS; and wherein the third calibration signals do not pass through the filter array during said transmitting third calibration signals through each of the plurality of third calibration loops.
15. The method of claim 14 , wherein the first calibration signals, the second calibration signals, and the third calibration signals are transmitted at a first frequency within a frequency band of an antenna within the AAS.
16. The method of claim 15 , wherein the factory calibration data and the field calibration data are generated across multiple frequencies within the frequency band.
17. The method of claim 13 , wherein the AAS comprises a multi-stage switch network electrically coupled to the reference transmitter and the reference receiver; and wherein each of the first, second and third calibration loops pass through respective portions of the multi-stage switch network.
18. A method of generating calibration data in an active antenna system (AAS) radio, comprising:
transmitting first calibration signals through a plurality of first calibration loops, which include respective filters and in-line directional couplers within a multi-channel transmit/receive signal path of the AAS radio, with said in-line directional couplers located on a transmit side of the filters within the AAS radio,
wherein a removable routing network is electrically coupled to antenna-side terminals of the filters; and wherein each of the first calibration signals passes, in sequence, through the routing network and to an antenna-side terminal of a respective one of the filters.
19. The method of claim 18 , wherein a removable 1:2 N routing network is electrically coupled to antenna-side terminals of the filters and to a calibration port of the AAS radio; and wherein each of the first calibration signals passes, in sequence, through the routing network, and then to an antenna-side terminal of a respective one of the filters, and then to a respective in-line coupler, where N is greater than two.