In some embodiments, the circuits (and methods) may include a reference generator configured to generate a reference signal. The circuits (and methods) may also include a signal presence detection module configured to perform calibration on itself, during a calibration phase, based upon the reference signal. The signal presence detection module may be further configured to receive an input signal. The signal presence detection module may be further configured to perform detection, during a signal amplitude detection phase, of a state of the input signal. According to some embodiments, the circuits (and methods) may include a peak detector of the signal presence detection module shared by the calibration and the detection. In some embodiments of the circuits (and methods), the reference generator may be unpowered during the signal amplitude detection phase. The calibration and the detection may share the peak detector based upon time division multiplexing.