Design of a 79 GHz short range radar using a Si/SiGe HBT technology

Each year worlwide, 1.2 million people die in road accidents and more than 50 million are injured. Within the European Union, each year, more than 40.000 fatalities and 1.7 million injuries are caused by road accidents. As it can be seen in Fig. 1, almost 90% of car accidents could be avoided or minimized by using Short Range and Long Range Radars (SRR and LRR, respectively) which would detect dangerous driving situations, warn the drivers, help them to prevent or at least to minimize accidents. Silicon Germanium (SiGe) hetero-junction bipolar transistor (HBT) has been identified as the chip technology which may fulfill the technological requirements and the cost constraints and which might be an excellent alternative to expensive technologies such as GaAs which are not perfectly suited for mass market applications such as automotive radars.

Figure 1: Causes of collisions

With the funding of the German Ministry of Education and Research (BMBF) the joint research project Automotive high frequency electronics – KOKON was started in September 2004. The KOKON consortium consists of two semiconductor companies (Atmel and Infineon), two automotive radar sensor manufacturers (Bosch and Continental Temic), and one automobile company (DaimlerChrysler) supported by institutes and universities. Within the KOKON project the development of both 77 GHz LRR and 79 GHz SRR radar chip technology is investigated. The Competence Center is responsible for the design of the complete SRR front-end. The specifications for the 79 GHz SRR systems are:

  • Frequency 79 GHz
  • Bandwidth 4000 MHz
  • Maximum field of view +/- 80°
  • Range 30 m
  • Range Accuracy +/- 5 cm
  • Bearing accuracy +/- 5°

An overview of the various possible applications of the LRR and SRR is presented in Fig. 2.

Figure 2: Overview of various kind of applications for LRR and SRR