Patent ID: 7698077

Claim:
An electronic signal level detection system comprising: a comparison circuit having a first input to receive an analog input signal having a variable voltage, the comparison circuit comparing the input signal voltage to a threshold and supplying a comparator signal at an output for input signal voltages exceeding the threshold; a detector having an input to receive the comparator signal and an output to supply detection signals responsive to receiving comparator signals in a periodic first time frame; a counter having an input to receive the detection signals and an output to supply a count in a periodic second time frame following the first time frame; a digital-to-analog converter (DAC) having an input to receive the count and having an output to supply a threshold voltage, for adjusting the threshold and creating a metric representative of the difference between the input signal voltage and the threshold in response to the count; wherein the counter increments the count in response to receiving a detection signal in the first time frame, and decrements the count in response to not receiving a detection signal in the first time frame; and, wherein the detector is a detection register setting a detection register output to a first value in response to receiving a comparator signal, and setting the detection register output to a second value, different from the first value, in response to not receiving a comparator signal.