  Beam training is one of the most important and challenging tasks in
millimeter-wave and sub-terahertz communications. Novel transceiver
architectures and signal processing techniques are required to avoid
prohibitive training overhead when large antenna arrays with narrow beams are
used. In this work, we leverage recent developments in wide range
true-time-delay (TTD) analog arrays and frequency dependent probing beams to
accelerate beam training. We propose an algorithm that achieves high-accuracy
angle of arrival estimation with a single training symbol. Further, the impact
of TTD front-end impairments on beam training accuracy is investigated,
including the impact of gain, phase, and delay errors. Lastly, the study on
impairments and required specifications of resolution and range of analog delay
taps are used to provide a design insight of energy efficient TTD array, which
employs a novel architecture with discrete-time sampling based TTD elements.
