Hiroshima University and Mie Fujitsu Semiconductor Limited (MIFS) have together developed a low-power millimeter-wave amplifier that operates at a frequency range from 80 GHz to 106 GHz and requires a 0.5 V power supply. It was fabricated using MIFS's Deeply Depleted Channel (DDC) technology. To our knowledge, this is the first W-band (75 to 110 GHz) amplifier that can operate at such a low power-supply voltage. Details of the technology were presented at the IEEE Radio Frequency Integrated Circuits Symposium (RFIC) 2017, in Honolulu, Hawaii.
The W-band is the frequency range starts at 75 GHz up to 110 GHz and is used by automotive radars. Sophisticated driver-assistance and self-driving will require radars with millimeter-wave beam scanning capability that can identify objects during the day and night even in adverse weather conditions. This can be done using a phased array that consists of hundreds of transmitters and receivers. As battery-powered cars become more common, it is imperative that these circuits consume as little power as possible. Lowering the power-supply voltage is the most effective means of accomplishing low power consumption. However, transistor performance drops with voltage and no W-band amplifier has so far operated at as low as 0.5 V. The research team successfully demonstrated a W-band amplifier at 0.5 V by bringing together MIFS's DDC technology and design techniques developed by Hiroshima University. The DDC technology offers high-performance silicon MOS transistors even at low voltages and is currently available from MIFS as a 55-nm CMOS process. The design techniques further improve transistor and circuit performance at millimeter-wave frequencies.
With this breakthrough, low-power W-band circuits really seem possible and applications aren't limited to automotive radars and high-speed communications between base stations. What if you have a radar on your smartphone? Today's smartphones can already sense things like acceleration, audible sound, visible light, and Earth's magnetic field. But the only active probing device is that tiny LED (light-emitting diode) that can illuminate at most a few meters. Add a millimeter-wave radar on a smartphone, and it doesn't have to be a so-called primary radar, which only detects waves reflected back. Your smartphone could respond to waves from your friend's radar and send some signal back. This technology has a wide range of applications.
