ADAPTIVE ADC CONTROL FOR LIVING OBJECT PROTECTION
Certain aspects of the present disclosure generally relate to methods and apparatus for adaptively controlling an analog-to-digital converter (ADC), such as an ADC in a living or moving object detection system integrated into a base pad of a wireless power transmitter. One example method for operating an object detection system generally includes sampling a radar input signal with an ADC of the object detection system, determining an actual radar signal level based on the sampled radar input signal, comparing the actual radar signal level with a target radar signal level, and adjusting one or more parameters of the ADC based on the comparison.
1 . A method for operating an object detection system, comprising:
sampling a radar input signal with an analog-to-digital converter (ADC) of the object detection system;
determining an actual radar signal level based on the sampled radar input signal;
comparing the actual radar signal level with a target radar signal level; and
adjusting one or more parameters of the ADC based on the comparison.
2 . The method of claim 1 , further comprising:
receiving the radar input signal via one of a plurality of radar modules of the object detection system; and
detecting a presence of an object in a detection area of at least one of the radar modules, based on the sampled radar input signal.
3 . The method of claim 1 , wherein the comparing comprises:
determining a difference between the target radar signal level and the actual radar signal level; and
comparing the difference with a threshold.
4 . The method of claim 1 , wherein the one or more parameters comprise a reference voltage for the ADC.
5 . The method of claim 4 , wherein the adjusting comprises controlling a digital-to-analog converter (DAC) configured to generate the reference voltage for the ADC.
6 . The method of claim 5 , wherein the DAC receives a control signal based on the comparison and another reference voltage and wherein the reference voltage for the ADC is based on the control signal and the other reference voltage.
7 . The method of claim 1 , wherein the adjusting comprises generating at least one control signal configured to adjust the one or more parameters of the ADC based on the comparison.
8 . The method of claim 1 , wherein the determining comprises determining a mean of the sampled radar input signal over a period.
9 . The method of claim 1 , wherein the determining comprises continuously determining the actual radar signal level, once per sample period of the ADC.
10 . The method of claim 1 , further comprising:
receiving the radar input signal via one of a plurality of radar modules of the object detection system; and
calculating the target radar signal level before the comparison based on one or more characteristics of the plurality of radar modules.
11 . The method of claim 1 , further comprising calculating the target radar signal level before the comparison.
12 . An apparatus for object detection in a wireless power transfer application, comprising:
an analog-to-digital converter (ADC) configured to sample a radar input signal; and
a processor having an input coupled to an output of the ADC and configured to:
determine an actual radar signal level based on the sampled radar input signal;
compare the actual radar signal level with a target radar signal level; and
output at least one control signal configured to adjust one or more parameters of the ADC based on the comparison.
13 . The apparatus of claim 12 , further comprising a plurality of radar modules, at least one of the radar modules being configured to receive a radio frequency (RF) signal and to process the RF signal to generate the radar input signal, wherein the processor is further configured to detect a presence of an object in a detection area of the at least one of the radar modules, based on the sampled radar input signal.
14 . The apparatus of claim 12 , wherein the processor is configured to compare the actual radar signal level with the target radar signal level by:
determining a difference between the target radar signal level and the actual radar signal level; and
comparing the difference with a threshold.
15 . The apparatus of claim 12 , wherein the one or more parameters comprise a reference voltage for the ADC.
16 . The apparatus of claim 15 , further comprising a digital-to-analog converter (DAC) configured to generate the reference voltage for the ADC.
17 . The apparatus of claim 16 , wherein the ADC comprises:
a comparator having a first input coupled to a node with the radar input signal and a second input coupled to an output of the DAC; and
a sampler having an input coupled to an output of the comparator.
18 . The apparatus of claim 16 , wherein:
the DAC has an input coupled to an output of the processor;
the DAC is configured to receive the control signal and another reference voltage; and
the reference voltage for the ADC is based on the control signal and the other reference voltage.
19 . The apparatus of claim 12 , wherein the processor is configured to determine the actual radar signal level by determining a mean of the sampled radar input signal over a period.
20 . The apparatus of claim 12 , wherein the processor is configured to determine the actual radar signal level by determining the actual radar signal level once per several sample periods of the ADC.
21 . The apparatus of claim 12 , further comprising a plurality of radar modules, at least one of the radar modules being configured to receive a radio frequency (RF) signal and process the RF signal to generate the radar input signal, wherein the processor is further configured to calculate the target radar signal level before the comparison based on one or more characteristics of the plurality of radar modules.
22 . The apparatus of claim 12 , wherein the processor is further configured to calculate the target radar signal level before the comparison.
23 . An apparatus for object detection in a wireless power transfer application, comprising:
means for sampling a radar input signal;
means for determining an actual radar signal level based on the sampled radar input signal;
means for comparing the actual radar signal level with a target radar signal level; and
means for adjusting one or more parameters of the means for sampling based on the comparison between the actual radar signal level and the target radar signal level.
24 . The apparatus of claim 23 , wherein the means for comparing is configured to:
determine a difference between the target radar signal level and the actual radar signal level; and
compare the difference with a threshold.
25 . The apparatus of claim 23 , wherein the one or more parameters comprise a reference voltage for the means for sampling.
26 . The apparatus of claim 25 , further comprising means for generating the reference voltage for the means for sampling, wherein the means for adjusting is configured to control the means for generating.
27 . The apparatus of claim 26 , wherein the means for generating is configured to receive a control signal based on the comparison and another reference voltage and wherein the reference voltage for the means for sampling is based on the control signal and the other reference voltage.
28 . The apparatus of claim 23 , wherein the means for determining is configured to determine a mean of the sampled radar input signal over a period.
29 . The apparatus of claim 23 , further comprising:
means for receiving a radio frequency (RF) signal;
means for processing the RF signal to generate the radar input signal; and
means for detecting a presence of an object in a detection area of the means for receiving, based on the sampled radar input signal.
30 . The apparatus of claim 23 , further comprising:
means for receiving a radio frequency (RF) signal;
means for processing the RF signal to generate the radar input signal; and
means for calculating the target radar signal level for the means for comparing, based on one or more characteristics of at least one of the means for receiving or the means for processing.