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Mimo mid-range radar for security applications in mainstream CMOS technology

Final Report Summary - MIRAMOS (Mimo mid-range radar for security applications in mainstream CMOS technology)

Security has become a global issue since the 9-11 incident. This event indicated the embarking of a new episode in the history of mankind which should have been associated with the security concerns. Although a large assortment of security devices have been put in action to prevent the happening of world shaking events as above, the static nature of the available equipment has limited its applicability. In fact, it has stimulated the development of cheap, accurate, pocket size and flexible imaging systems which must be capable of serving a large variety of security applications across the landscape of public services and places e.g. airports, train stations, schools, etc. Therefore, the MIRAMOS project was defined to investigate a portable security system which is suitable to short range applications.

In this project, a radar system is investigated to track objects for security purposes. Radar is an object detection system that uses electromagnetic waves to identify the range, altitude, direction, and / or speed of both moving and fixed objects such as aircrafts, ships, motor vehicles, weather formations, and terrain. The information provided by radar includes the bearing and position of the object. It is used in a wide range of applications. Initially, radar is mainly used for military purposes. However, it has rapidly evolved in the civilian field into applications for aircraft, ships, roads, etc. The basic idea of radar is that it transmits microwaves which bounce off from any object in their path. The object returns a certain part of the source's energy to a receiver. The time it takes for the reflected waves to return to the receiver enables a computer to calculate the distance to the object, its radial velocity and other characteristics as well.

This report describes concepts, mathematical background, and simulations for a low-cost monopulse radar design operating at 60 GHz and suitable for implementation in mainstream CMOS. The concepts of frequency-modulated continuous wave (FMCW) radar, monopulse radar, and beam-forming, are first explained separately. Next, a radar system that uses all these concepts in a combined way is analysed on its functional behaviour and its sensitivity to variations in implementation in mainstream CMOS.

This project focused on the system level optimisation of the accuracy of the radar to detect objects. Two important findings are presented as the major highlights of this project. First is about the time delay to phase delay consideration. Conventionally, only in narrow band system, the phase shift can be approximated as time delay, but in the proposed system, by proper defining the IF frequency, the error in this approximation can be easily reduced to less than 1 %. Another important conclusion is that swapping of signal paths can be used to cancel the phase errors in different paths. As long as the errors can be extracted from the two different operations, the error can be removed. The two findings are very important in radar for angle detection. The basic blocks of the proposed system are also designed for a 65 nm CMOS technology. Simulation results at circuit level agree well with system simulations, what demonstrates the feasibility of achieving such a portable radar system in standard CMOS technology.