21.2 A 3-to-10GHz 180pJ/b IEEE802.15.4z/4a IR-UWB Coherent Polar Transmitter in 28nm CMOS with Asynchronous Amplitude Pulse-Shaping and Injection-Locked Phase Modulation

Abstract

The recent popularity of indoor-localization applications such as secure access and asset tracking has led to growing interest in accurate RF-based ranging solutions. Impulse-radio ultra-wideband (IR-UWB) is a promising solution for accurate ranging due to its wideband 0peration. The recently released IEEE 802. 15.4z standard [1] improves upon the security of ranging and mandates a coherent operation with higher mean pulse-repetition frequencies (mPRF), in comparison to the legacy standard IEEE 802. 15.4a. The next generation IR-UWB devices demand ultra-low-power operation while meeting the strict spectrum regulations to operate worldwide in C and X bands (4 to 10GHz). The prior-art coherent IR-UWB transmitters either consume very high power [2] or result in high spurious emissions in adjacent channels due to poor sidelobe suppression [3 –6]. In this work, an asynchronous polar transmitter is proposed that consumes 4.9mW active power with an output power spectral density (PSD) of -41.3dBm/MHz and a sidelobe suppression of over 28dBrin IEEE 802. 15.4zl24.8MHzmPRF mode, channel 9 (7987.2MHz). Further, we demonstrate the use of an injection-locked ring oscillator (IL-R0) with fine-grained duty-cycling of the TX chain to achieve state-of-the-art power consumption for mPRFs from 3.9MHz to 124. 8MHz while maintaining coherent operation over the packet.