A Quadrature Uncertain-IF IR-UWB Transceiver with Twin-OOK Modulation

Benefiting from good energy efficiency and fine ranging accuracy, impulse-radio ultra-wideband (IR-UWB) has been revived recently for short-distance communications. The I R-UWB transceiver, however, faces two major issues because of using short-duration pulses. Firstly, the short-duration pulse brings synchronization difficulty to the baseband. Even though the standard-compliant preamble [1] or the synchronized-OOK (S-OOK) modulation [2] provides a way for the baseband synchronization, they suffer from degraded energy efficiency or reduced link margin. Secondly, the IR-UWB receiver has a design trade-off between power consumption and demodulation performance. Having a simple architecture and intermittent operation, the noncoherent UWB receiver consumes less power than the coherent UWB receiver, but the demodulation performance is vulnerable to noise and interference. Recently, an uncertain-IF UWB receiver [3], employing a two-step downconversion, not only inherits the advantages of a low-power noncoherent architecture but also improves the sensitivity and the narrowband interference (NBI) tolerance, thus overcoming the disadvantages of the noncoherent demodulation as well. However, in order to achieve a fine ranging accuracy, a high IF is required in the uncertain-IF UWB receiver. In this work,
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propose a low-power UWB transceiver architecture with two novel features. One is a twin-OOK (T-OOK) modulation that not only achieves the baseband synchronization efficiently but also improves the spectrum efficiency by applying a frequency-hopping (FH) method. The other is a quadrature uncertain-IF demodulation to improve the ranging accuracy without requiring a high IF. A 6-to-8GHz IR-UWB transceiver based on the proposed methods achieves energy-efficient baseband synchronization, improved spectrum efficiency, good NBI tolerance and 1 cm ranging accuracy.