Millimeter-Wave Radar for Low-Power Applications

Radar technology has developed rapidly during the last century. Besides its initial use for military, it is nowadays also applied for many civil applications. Improvements in circuit technology make integrated radar sensors possible, allowing a significant reduction of the production cost. Integrated radio circuits in the low gigahertz range are widely available, not least driven by wireless communications. Even circuits at millimeter-wave frequencies are available, as they, for instance, are used for automotive radar. New semiconductor materials, devices, and circuit topologies offer interesting possibilities to increase the operation frequency and to reduce the power-consumption of radar circuits. With these developments, novel applications might open up, for instance the integration of radar in battery powered devices.

In this thesis, different aspects of developing low-power millimener-wave radar technology are investigated. An efficient, coherent radar pulse generator is implemented. The circuit is based on a resonant-tunneling diode implemented with III-V semiconductors. A fast metal-oxide-semiconductor field-effect transistor is used to shape short pulses. A novel modulation technique is presented, enabling the generation of a phase modulated radar waveform, without additional power loss. Various low-power radar applications of the circuit are investigated. The characterization of porcine-skin is demonstrated, which might open up biomedical applications. It is shown that the scattering of low-power pulses on different hand postures can be detected with a pulsed radar. A setup for the real time acquisition of hand gestures with a pulsed radar is implemented and the successful classification of 12 hand gestures is demonstrated. Using this technique low-power systems with low duty cycle waveforms might be implemented.