An apparatus includes a log amplifier and a calibration circuit. The log amplifier may be configured to generate an output signal in response to an offset between a first voltage and a second voltage. The calibration circuit may be configured to disconnect an input power and perform a cancellation of the offset when the input power is not present. The first voltage may be generated by the apparatus in response to a power detection. The second voltage may be received from a reference circuit. The cancellation of the offset may extend a working range of the apparatus. The output may provide a linear-in-dB power detection.