IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 42, NO. 11, NOVEMBER 2007 2515 A CMOS Ultra-Wideband Receiver for Low Data-Rate Communication Julien Ryckaert, Student Member, IEEE, Marian Verhelst, Student Member, IEEE, Mustafa Badaroglu, Stefano D’Amico, Member, IEEE, Vincent De Heyn, Claude Desset, Member, IEEE, Pierluigi Nuzzo, Student Member, IEEE, Bart Van Poucke, Piet Wambacq, Member, IEEE, Andrea Baschirotto, Senior Member, IEEE, Wim Dehaene, Senior Member, IEEE, and Geert Van der Plas, Member, IEEE Abstract—A low-power impulse-radio ultra-wideband receiver is demonstrated for low data-rate applications. A topology selec- tion study demonstrates that the quadrature analog correlation is a good receiver architecture choice when energy consumption must be minimized. The receiver operates in the 3.1–5 GHz band of the UWB FCC spectrum mask on channels of 500 MHz bandwidth. The pulse correlation operation is done in the analog domain in order to reduce the ADC sampling speed down to the pulse repetition rate, thereby reducing the power consumption. The receiver comprises a low-noise amplifier with full on-chip matching network, an RF local oscillator generation, two quadra- ture mixers, two analog baseband chains followed by two ADCs, and a clock generation network. The receiver is implemented in 0.18 m CMOS technology and achieves 16 mA power consump- tion at 20 Mpulses/s pulse repetition rate. Index Terms—CMOS integrated circuits, direct-conversion, low- power electronics, pulse-position modulation, receivers, RF, ultra- wideband (UWB). I. INTRODUCTION T HE evolution of our society towards an environment proposing ubiquitous communication anytime and any- where necessitates solutions to some technological gaps that have been overlooked in the race for ever increasing data rates. Consequently, applications where power consumption is the leading metric have recently gained strong interest from the wireless community. Ahead of these applications, sensor net- works are required to bridge important technological obstacles such as ultra-low-power consumption along with miniaturized size. For such applications, the wireless radio must obviously find methods of trading communication performance for power consumption. Manuscript received November 8, 2006; revised May 5, 2007. The work of M. Verhelst was supported by a fellowship from the Fund for Scientific Re- search–Flanders (Belgium) (FWO-Vlaanderen) J. Ryckaert and P. Wambacq are with IMEC, 3001 Leuven Belgium, and also with Vrije Universiteit Brussel, 1050 Elsene, Belgium (e-mail: ryckj@imec.be). M. Verhelst and W. Dehaene are with Katholieke Universiteit Leuven, 3001 Leuven, Belgium. M. Badaroglu is with AMI Semiconductor Belgium, 9700 Oudenaarde, Bel- gium. S. D’Amico and A. Baschirotto are with Universita degli studi di Lecce, 73100 Lecce, Italy. V. De Heyn, C. Desset, B. Van Poucke, and G. Van der Plas are with IMEC, 3001 Leuven, Belgium. P. Nuzzo is with IMEC, 3001 Leuven, Belgium, and also with Universita di Pisa, 56122 Pisa, Italy. Digital Object Identifier 10.1109/JSSC.2007.907195 Some works have demonstrated the potential of impulse radio ultra-wideband (IR-UWB) communication as a solution to over- come the energy gap [1]–[6] of sensor networks. Moreover, the IEEE 802.15.4a standardization committee [7] has recently been formed to propose a physical layer for low-power sensor network communication using IR-UWB as a key technology. However, IR-UWB brings its own challenges. Although low- power solutions have been demonstrated for transmitters [3], the design of the receiver remains very challenging. The large bandwidth requirements of the analog front-end and baseband circuits, the high sampling rates in the digital conversion, the high timing precision and signal synchronization are still im- pediments for the realization of a low-power UWB receiver. In this work, we demonstrate the feasibility of a low-power UWB receiver through implementation. Supported by a careful ar- chitectural tradeoff analysis where various topologies are ex- plored, the optimal architecture is selected for hardware imple- mentation. A single-chip receiver realized in a standard 0.18 m CMOS technology [8] is then described without any external components (besides an external 20 MHz crystal oscillator) so as to satisfy the size and cost requirements of sensor network applications. The paper is organized as follows. Section II specifies the communication air interface for the receiver. Section III ana- lyzes various receiver topologies and compares them based on performance and power consumption. This analysis leads to the selection of a topology whose architecture and specifica- tions are derived in Section IV. Section V then describes the re- ceiver implementation providing individual building-block de- sign guidelines and measured performances. Section VI shows the overall system measurement results and Section VII con- cludes the paper with some future work. II. IR-UWB AIR INTERFACE The receiver is targeted for the 3.1–5 GHz UWB band. Since the minimum bandwidth of an UWB signal is 500 MHz, the 3.1–5 GHz band can be subdivided in different sub-bands. This subdivision offers a solution to mitigate strong interferers, im- proves the multiple access freedom, and allows to adapt with different regulation masks on UWB emissions worldwide. In this work, the receiver has been made flexible to supply three 500 MHz channels in the lower 3.1–5 GHz UWB band. The receiver has been optimized for the reception of carrier-based impulses [3]. 0018-9200/$25.00 © 2007 IEEE