ULTRA-WIDEBAND (UWB), which is regulated for commercial use of the band 3.1-10.6 GHz by Federal Communication Commission (FCC), has recently emerged as a promising technology for short-range wireless data communications [1]. Impulse radio (IR-UWB) approach which uses short-duration impulses modulated in time, polarity is attractive for low-cost, low-power, low data rate wireless communication applications such as RF Tag [2], wireless sensor network [3], and wireless body area network (WBAN) [4]. IR-UWB has also drawn much attention from the researchers as well as industries with a number of advantages including robustness to multi-path fading, lower interferences to existing communication systems, and precise localization capability due to the very short pulse nature. By IEEE 802.15.4a Task Group [5], IR-UWB has been chosen as a candidate to deliver communications and high precision ranging. Moreover, IR-UWB system can operate in burst-like scheme with low duty cycle, short-active and long-sleep period, leading to a substantial reduction in power consumption.
This thesis presents the design and implementation of an energy-efficient low-complexity CMOS transceiver for IR-UWB application. The ultra lowpower, low-complexity UWB transmitter operates over three 528 MHz subbands in 3-5 GHz band. It consists of an On-Off Keying (OOK) modulator and a key block, pulse generator. The short pulses are generated based on the ON/OFF switching operation of an oscillator with subband switching functionality which is mandatory for multiband IR-UWB systems. The relation between the oscillator switching operation and the resulting output pulse envelope, which determines pulse spectral characteristics, is analyzed and the design guidelines for topology and component values are presented. Measurements show a pulse duration of 3.5 ns and a spectrum that fully complies with the FCC spectral mask with more than 20 dB of sidelobe rejection without the need for additional filtering. Maximum pulse rate is up to over 200 MHz. Implemented in $0.18\mum$ CMOS technology, the transmitter operates in burst mode and dissipates only 18 pJ of energy consumption per pulse. The transmitter is best suited for energy detection receivers.
In the receiver, an ultra low-power non-coherent energy detection (ED) receiver is proposed and implemented. The proposed low-complexity ED receiver consists of a wideband LNA, a squarer, an analog integrator, and a comparator. The main target is to reduce the power consumption and complexity thus the cost of the design. The whole receiver is designed to minimize the baseline current and to operate in bust mode, which dissipate only dynamic current. The ED receiver dissipates only 450uA of static current. The receiver shows over 13 dB of NF and a minimum detectable signal level is -60 dB. Transceiver die size is 1.3 mm$\times$1mm, which is very compact.
