9.3 A 1mW 1Mb/s 7.75-to-8.25GHz chirp-UWB transceiver with low peak-power transmission and fast synchronization capability

Future binaural hearing-aid devices face severe energy constraints on the wireless links where the ear-to-ear link enables signal processing of sound for both ears to enhance speech intelligence and the ear-to-device link provides an audio channel to commercial electronics such as smart TVs, MP3 players, and smart phones. Due to the limited size of the battery (35 to 90mAh) especially for in-the-ear (ITE) and in-the-canal (ITC) types, a sub-mW transceiver is required for long operational time. A low-data-rate impulse-radio ultra-wideband (IR-UWB) transceiver [1] achieves low power consumption with aggressive duty-cycled operation, namely 1%, but suffers from the bit-level synchronization problem by the baseband. Moreover, the low-data-rate IR-UWB exhibits a high peak transmission power to maintain a sufficient average transmission power for the given link margin. The constant-envelope frequency-modulated ultra-wideband (FM-UWB) system in [2,3] features a low peak voltage and a steep roll-off spectrum, but the lack of duty-cycled operation makes it difficult to achieve low power. Narrowband WBAN transceivers such as the Bluetooth Low Energy (BLE) transceiver [4,5] offer good compliance with existing wireless SoCs, but the sub-mW power consumption is not feasible and they have a potential coexistence problem with existing Bluetooth devices. In this paper, a chirp-FSK-based UWB transceiver is proposed to significantly reduce the peak transmission power with relaxed duty-cycled operation for noninvasive, energy-efficient, and agile short-range communications.