Published in IET Circuits, Devices & Systems Received on 27th February 2009 Revised on 29th June 2009 doi: 10.1049/iet-cds.2009.0055 ISSN 1751-858X 24-GHz ultra-wideband transmitter for vehicular short-range radar applications A. Scuderi 1 E. Ragonese 2 G. Palmisano 2 1 STMicroelectronics, Stradale Primosole 50, Catania 95121, Italy 2 Universita ` di Catania, Facolta ` di Ingegneria, DIEES, Viale A. Doria 6, Catania 95125, Italy E-mail: eragonese@diees.unict.it Abstract: This paper presents a 24-GHz transmitter for ultra-wideband short-range radar applications fabricated in a 0.13-mm SiGe:C BiCMOS technology. The circuit is composed of a frequency synthesiser, based on 24-GHz voltage-controlled oscillator in an N-integer phase-locked loop (PLL), a RF switch delivering a 0-dBm output power, and a tunable rectangular pulse generator, whose pulse width covers a range between 0.5 and 1.2 ns. The transmitter has been developed for a flip-chip bumping assembly on a module with an UWB antenna. Assuming a 10.5-dBi antenna gain, it is compliant with European Telecommunications Standards Institute (ETSI) transmission mask and is able to cover the main automotive applications addressing both a resolution better than 0.1 m and maximum unambiguous range of 15 m. 1 Introduction Innovative driver assistance systems and/or active safety functions are becoming the most attractive solution to reduce the impressive number of car accidents with fatalities. In this scenario, radar systems are considered the eligible technology covering both safety and comfort functionalities for vehicular drivers. Alternatively, ultrasonic, video, laser or infrared sensors present serious drawbacks to guarantee efficient systems. Indeed, although ultrasonic sensors are very compact and cheap, they work in few metres (less than 2 m), whereas video, laser and infrared sensors offer excellent operative distance range but they are strongly affected by unpredictable scenario conditions (rain, fog, dust etc.). On the other hand, radar sensors feature excellent range and speed accuracy and they can be easily mounted under plastic panels (i.e. bumpers) without affecting the car appearance. To achieve a complete inspection around the car, a radar system takes advantage of two classes of sensors. Long-range radar (LRR) sensors cover a limited angle (+108) ahead of the car at distances of few metres to about 150 m and are typically used for autonomous cruise control (ACC) applications. Short-range radar (SRR) sensors cover a significant part of the azimuth angle and look around the car (100–3608) at distances up to 15– 30 m. Several SRR sensors, properly placed around the car, are able to detect a target in a range from 0.1 to 15 – 30 m, thus enabling a variety of applications concerning both comfort and safety fields, such as pre- crash sensing, collision mitigation, blind spot detection, parking aid, lane change assistant, rear crash collision warning, stop&go and urban collision avoidance [1]. In Table 1 SRR sensor requirements of the most common applications are compared in terms of detection range, resolution, relative velocity, acquisition time and category of sensor. The last two columns highlight the applications that can be addressed by both technologies, SRR and LRR, producing an advanced driver-assisted system. In spite of the growing importance of radar systems, a global standardisation is not yet achieved. Regulation institutes, such as the Federal Communication Commission (FCC) and the European Telecommunications Standards Institute (ETSI), recently allocate unlicensed bands for ultra-wideband (UWB) SRR in USA and EU, respectively. In 2002, the FCC regulation indicates a band as large as 7 GHz between 22 and 29 GHz allowed for SRR devices [2]. In order to support the development of UWB SRR systems in commercial silicon-based technology, the EU permits the temporary use of a band between 22 and 26.625 GHz until June 2013 [3]. From 2013, new cars IET Circuits Devices Syst., 2009, Vol. 3, Iss. 6, pp. 313–321 313 doi: 10.1049/iet-cds.2009.0055 & The Institution of Engineering and Technology 2009 www.ietdl.org