Impulse radio UWB (IR-UWB) is widely known for its potentials of providing high precision on localization. To fully take advantage of IR-UWB, errors introduced by circuits or signal processing need to be reduced as small as possible. In this paper, we focus on the IR-UWB transceiver. We revisit our previously implemented IR-UWB transceiver, where a fixed time bias was adopted to compensate the time difference between the time that an IR-UWB pulse is physically detected and the time that the detection of pulse is noticed inner transceiver. We find that the ranging error varies with distance, which can’t be well reflected by a fixed time bias. By replacing the fixed time bias with an adaptive time bias, we show that the ranging error is reduced approximately 58%. We further examine the effect of the adaptive time bias on localization and confirm that localization accuracy can be improved accordingly.