Patent ID: 7974598

Claim:
A received signal strength indicator detector, comprising: an amplifier and rectifier stage configured to convert a received radio frequency signal having a signal power level into a direct current signal and to output an indicator value corresponding to the signal power level; and a calibration circuit configured to measure a maximum value of the indicator value based on a maximum value of the signal power level and to bias the indicator value according to a bias factor calculated based on the measured maximum indicator value, a desired maximum indicator value, a desired indicator threshold, and a desired power range of the received signal strength indicator wherein the calibration circuit includes a comparator, a calculation circuit, and an adjustable current source coupled in series, wherein the bias factor includes an offset factor, and wherein the comparator is configured to determine a differential signal (V diff ) as follows: V diff =V designed — RSSI −V measured — RSSI where V designed — RSSI is the desired maximum indicator value and V measured — RSSI is the measured maximum indicator value; the calculation circuit is configured to calculate the offset factor as follows: Offset_Factor = V threshold V range × V diff where V threshold is the desired indicator threshold and V range is the desired power range; and the adjustable current source is configured to bias a subsequently measured indicator value (V Raw — RSSI ) with the offset factor as follows: V calibrated — RSSI =V Raw — RSSI +Offset_Factor or V calibrated — RSSI =V Raw — RSSI −Offset_Factor where V calibrated — RSSI is the calibrated indicator value.