Abstract: A near field communications (NFC) device is disclosed that detects an envelope of a radio frequency (RF) signal. The NFC device includes a peak detector that determines the envelope of the RF signal. The peak detector compares a first differential signal voltage to a second differential signal voltage. The peak detector delays a rising edge of a first differential signal and provides the first differential signal voltage to the peak detector output when the first differential signal voltage is greater than the second differential signal voltage. The peak detector delays a falling edge of a second differential signal and provides the second differential signal voltage to the peak detector output when the second differential signal voltage is greater than the first differential signal voltage.