Proximity-independent SAR mitigation
A radiofrequency (RF) power regulator includes a forward RF power detection circuit to detect forward RF power supplied by an RF transmitter circuit to an RF transmitting antenna. An RF power sampler is coupled to the forward RF power detector circuit and provides RF power samples of the supplied forward RF power. Multiple filters are coupled to receive the RF power samples. Each filter differently filters the received forward power samples to apply a different average power period. Each filter activates an RF power adjustment trigger signal while a time-averaged forward RF power supplied to the RF transmitting antenna satisfies a forward RF power adjustment condition for the average power period of the filter. Forward RF power adjustment logic is coupled to filters and operable to adjust the forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna based on the RF power adjustment trigger signal.
1. A method of regulating forward radiofrequency (RF) power supplied by an RF transmitter circuit to an RF transmitting antenna, the method comprising:
detecting the forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna;
monitoring RF power samples of the supplied forward RF power over at least one average power period;
activating an RF power adjustment trigger signal while a time-averaged forward RF power supplied to the RF transmitting antenna satisfies a forward RF power adjustment condition for the at least one average power period, the forward RF power adjustment condition specifying a relation between the time-averaged forward RF power supplied to the RF transmitting antenna during the at least one average power period and a first predetermined time-averaged power threshold; and
adjusting the forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna based on the RF power adjustment trigger signal.
2. The method of claim 1 wherein the at least one average power period includes a plurality of average power periods, wherein the monitoring operation is performed at multiple filters, each filter differently filtering the monitored RF power samples to apply a different average power period of the plurality of average power periods.
3. The method of claim 2 further comprising:
selecting one of the multiple filters from which to output the RF power adjustment trigger signal.
4. The method of claim 3 wherein the selecting operation selects one of the multiple filters based on at least one of network conditions and transmission requirements.
5. The method of claim 1 further comprising:
applying an attenuation profile while the RF power adjustment trigger signal is active, the adjusting operation adjusting the forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna according to the attenuation profile.
6. The method of claim 5 wherein the attenuation profile specifies magnitudes of incremental adjustments in forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna.
7. The method of claim 5 wherein the attenuation profile specifies durations of incremental adjustments in forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna.
8. The method of claim 1 wherein the detecting operation comprises:
isolating the forward RF power from reflected RF power in a supply coupling between the RF transmitter circuit and the RF transmitting antenna.
9. A radiofrequency (RF) power regulator comprising:
a forward RF power detection circuit configured to detect forward RF power supplied by an RF transmitter circuit to an RF transmitting antenna;
an RF power sampler coupled to the forward RF power detection circuit, the RF power sampler configured to provide RF power samples of the supplied forward RF power over at least one average power period;
at least one filter to monitor the RF power samples, the at least one filter activating an RF power adjustment trigger signal while a time-averaged forward RF power supplied to the RF transmitting antenna satisfies a forward RF power adjustment condition for the at least one filter, the forward RF power adjustment condition specifying a relation between the time-averaged forward RF power supplied to the RF transmitting antenna during the at least one average power period and a first predetermined time-averaged power threshold; and
forward RF power adjustment logic coupled to the at least one filter and configured to adjust the forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna based on the RF power adjustment trigger signal.
10. The RF power regulator of claim 9 wherein the at least one filter includes a plurality multiple filters, wherein each filter of the multiple filters differently filters the monitored RF power samples to apply a different average power period, and wherein the power regulator further comprises:
a filter selector coupled to the multiple filters and configured to select one of the multiple filters from which to output the RF power adjustment trigger signal.
11. The RF power regulator of claim 10 wherein the filter selector is configured to select one of the multiple filters based on at least one of network conditions and transmission requirements.
12. The RF power regulator of claim 9 further comprising:
an attenuation profile controller configured to apply an attenuation profile while the RF power adjustment trigger signal is active and to adjust the forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna according to the attenuation profile.
13. The RF power regulator of claim 12 wherein the attenuation profile specifies magnitudes of incremental adjustments or durations of incremental adjustments in forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna.
14. The RF power regulator of claim 9 wherein the forward RF power detection circuit comprises:
forward RF power isolation circuitry coupled between the RF transmitter circuit and the RF transmitting antenna and configured to isolate the forward RF power from reflected RF power in a supply coupling between the RF transmitter circuit and the RF transmitting antenna.
15. The RF power regulator of claim 14 wherein the forward RF power isolator circuitry comprises:
a directional coupler configured to detect the forward RF power from the supply coupling between the RF transmitter circuit and the RF transmitting antenna.
16. The RF power regulator of claim 14 wherein the forward RF power isolator circuitry comprises:
a directional coupler configured to detect the forward RF power from the supply coupling between the RF transmitter circuit and the RF transmitting antenna; and
a circulator coupled between the directional coupler and the RF transmitting antenna.
17. The power regulator of claim 9 , wherein the relation is the time-averaged forward RF power supplied to the RF transmitting antenna reaching or exceeding the first predetermined time-averaged power threshold, and wherein the forward RF power adjustment logic is configured to adjust the forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna based on the RF power adjustment trigger signal by reducing the forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna.
18. The power regulator of claim 9 , wherein the relation is the time-averaged forward RF power supplied to the RF transmitting antenna being less than the first predetermined time-averaged power threshold, and wherein the forward RF power adjustment logic is configured to adjust the forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna based on the RF power adjustment trigger signal by increasing the forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna.
19. The power regulator of claim 9 , wherein the first predetermined time-averaged power threshold is selected to be less than a second predetermined time-averaged power threshold to limit the time-averaged forward RF power supplied to the RF transmitting antenna from exceeding the second predetermined time-averaged power threshold.
20. One or more tangible processor-readable storage media devices embodied with instructions for executing on one or more processors and circuits of a computing device a process comprising:
detecting forward radiofrequency (RF) power supplied by a RF transmitter circuit to an RF transmitting antenna;
monitoring RF power samples of the supplied forward RF power over at least one average power period;
activating an RF power adjustment trigger signal while a time-averaged forward RF power supplied to the RF transmitting antenna satisfies a forward RF power adjustment condition for the at least one average power period, the forward RF power adjustment condition specifying a relation between the time-averaged forward RF power supplied to the RF transmitting antenna during the at least one average power period and a first predetermined time-averaged power threshold; and
adjusting the forward RF power supplied by the RF transmitter circuit to the RF transmitting antenna based on the RF power adjustment trigger signal.