Synchronized power and/or temperature measurement in a millimeter wave (MMW) front end module
A communications device including an array antenna assembly including a plurality of transmit chains, each with a transmit power amplifier, synchronously captures transmit power measurements for each power amplifier. A baseband transmitter in the communications device determines when a predetermined symbol in a protocol, e.g. a PSS SSB symbol, is to be transmitted and sends, e.g. via a SPI, a capture command to command each of the ADCs corresponding to the power amplifiers to synchronously capture a power measurement. Power measurements are captured at the boundary of the predetermined symbol, and the power measurements represent average transmit power levels corresponding to the symbol. The power measurements are communicated to the baseband transmitter which processes the data using calibration tables and taper information. Processed power measurements are compared to desired transmitter target levels and errors are determined. Based on the errors the gains of one or more TX chains are adjusted.
1. A method of operating a communication device, the method comprising:
operating a baseband transmitter to determine, based on a timing structure of a communications protocol, when a predetermined symbol will be transmitted;
operating the baseband transmitter to send a capture command to an address monitored by an SPI interface of a first chip in a transmission array included in said communications device; and
operating the first chip to capture one or more transmit power values, each of the one or more transmit power values being sensed at a point in time when an OFDM symbol boundary for the predetermined symbol is being output by the first chip to transmit antenna elements coupled to said first chip.
2. The method of claim 1 , wherein the communications device includes multiple chips.
3. The method of claim 2 , wherein operating the baseband transmitter to send a capture command is performed at a predetermined number of clock cycles prior to the occurrence of said OFDM symbol boundary.
4. The method of claim 2 , further comprising:
operating each of the multiple chips in the array to capture a temperature sensor value when the OFDM symbol boundary for the predetermined symbol is being output by the chips to corresponding antennas.
5. The method of claim 2 , wherein said multiple chips includes at least said first chip and a second chip, the method further comprising:
operating the first chip to store a first sensed transmit power value and a first sensed temperature value; and
operating the second chip to store a second sensed transmit power value and a second sensed temperature value.
6. The method of claim 5 , further comprising:
operating the baseband transmitter to use a first address corresponding to a first SPI interface of the first chip to retrieve the first sensed transmit power value and the first sensed temperature value; and
operating the baseband transmitter to use a second address corresponding to a second SPI interface of the second chip to retrieve the second sensed transmit power value and the second sensed temperature value.
7. The method of claim 6 , further comprising:
operating the baseband transmitter to use a first temperature calibration table to convert the first sensed temperature value to a first temperature.
8. The method of claim 7 , further comprising:
generating, based on the first temperature and a first power calibration table, a first scaled calibrated power detected level corresponding to the first chip.
9. The method of claim 8 further comprising:
comparing the first scaled calibrated power detected level corresponding to the first chip to a target power level for the first chip; and
determining that a power amplifier failure has occurred when the first scaled calibrated power detected level corresponding to the first chip differs from the target power level for the first chip by more than a first power amplifier fault threshold amount.
10. The method of claim 8 , further comprising:
summing scaled calibrated power detected levels corresponding to individual ones of said multiple chips to generate an estimated aggregate array power value;
operating the baseband transmitter to compare the estimated aggregate array power value to a target aggregate array power level for the baseband transmitter to generate an array power error; and
operating the baseband transmitter to change the gain of one or more transmit chains based on the array power error.
11. A communications device, the communications device comprising:
a transmission array including one or more chips, said one or more chips including a first chip; and
a baseband transmitter, said baseband transmitter including a first processor configured to:
operate the baseband transmitter to determine, based on a timing structure of a communications protocol, when a predetermined symbol will be transmitted; and
operate the baseband transmitter to send a capture command to an address monitored by an SPI interface of the first chip in the transmission array included in said communications device; and
wherein the first chip includes a second processor configured to:
operate the first chip to capture one or more transmit power values, each of the one or more transmit power values being sensed at a point in time when an OFDM symbol boundary for the predetermined symbol is being output by the first chip to transmit antenna elements coupled to said first chip.
12. The communications device of claim 11 , wherein the communications device includes multiple chips.
13. The communications device of claim 12 , wherein operating the baseband transmitter to send a capture command is performed at a predetermined number of clock cycles prior to the occurrence of said OFDM symbol boundary.
14. The communications device of claim 12 , wherein said multiple chips in the array includes said first chip and a second chip;
wherein said second chip includes a second processor;
wherein said first chip is configured to operate the first chip in the array to capture a temperature sensor value when the OFDM symbol boundary for the predetermined symbol is being output by the first chip to corresponding antenna elements; and
wherein said second chip is configured to operate the second chip in the array to capture a temperature sensor value when the OFDM symbol boundary for the predetermined symbol is being output by the second chip to corresponding antenna elements.
15. The communications device of claim 12 , wherein said multiple chips includes at least said first chip and a second chip, and wherein said second chip includes a third processor; and
wherein said second processor is further configured to operate the first chip to store a first sensed transmit power value and a first sensed temperature value; and
wherein said third processor is configured to operate the second chip to store a second sensed transmit power value and a second sensed temperature value.
16. The communications device of claim 15 , wherein said first processor is further configured to:
operate the baseband transmitter to use a first address corresponding to a first SPI interface of the first chip to retrieve the first sensed transmit power value and the first sensed temperature value; and
operate the baseband transmitter to use a second address corresponding to a second SPI interface of the second chip to retrieve the second sensed transmit power value and the second sensed temperature value.
17. The communications device of claim 16 , wherein said first processor is further configured to:
operate the baseband transmitter to use a first temperature calibration table to convert the first sensed temperature value to a first temperature.
18. The communications device of claim 17 , wherein said first processor is further configured to:
generate, based on the first temperature and a first power calibration table, a first calibrated power detected level corresponding to the first chip.
19. The communications device of claim 18 , wherein said first processor is further configured to:
sum calibrated power detected levels corresponding to individual ones of said multiple chips to generate an estimated aggregate array power value.
20. The communications device of claim 19 , wherein said first processor is further configured to:
operate the baseband transmitter to compare the estimated aggregate array power value to a target aggregate array power level for the baseband transmitter to generate an array power error; and
operate the baseband transmitter to change the gain of one or more transmit chains based on the array power error.