Millimeter-Wave CMOS Impulse Radio

Millimeter waves are electromagnetic waves with wavelengths of 1 to 10 mm in vacuum, and they were discovered experimentally in the 19th century (Wiltse, 1984). In 1946, the most unique feature of millimeter waves, oxygen absorption at 60 GHz, was reported, which results in the rapid attenuation of electromagnetic waves in the air (Beringer, 1946). Although the oxygen absorption makes long-distance wireless communication difficult, it enables us to allocate a wide frequency band, which realizes ultra-high-speed communication greater than 1Gbps (gigabits-per-second). Recently, the well-known feature of millimeter-wave communication has attracted attention again because millimeter-wave circuits have been realized with advanced CMOS technologies, and the recent 60GHz band license-free regulations with license-free bandwidths of 9GHz in Europe and 7GHz in Japan, USA, Canada and Korea. In academic conferences and journals, many studies on millimeterwave CMOS circuits were reported in the past few years, and consumer devices are expected to be available soon. Here, for realizing the consumer application of millimeter waves, the reduction of power consumption is the most important issue. It is noted that the power-hungry building blocks in a transceiver are the local oscillator (LO) based on the phase-locked loop (PLL), and analog-to-digital and digital-to-analog converters (ADC and DAC) as shown in Fig. 1(a) (Marcu, 2009). If these blocks can be eliminated partially or completely in a transceiver, power consumption will be considerably reduced. From this viewpoint, we have studied millimeter-wave pulse communication for high-performance CMOS wireless transceivers as shown in Fig. 1(b) and Fig. 1(c). In this study, low-power direct pulse generators, high-speed switches and receivers, which are the most important building blocks in millimeter-wave pulse communication, are discussed for high-speed wireless communications using the 60 GHz band. In conclusion, the prospects for millimeter-wave pulse communication will be addressed.