System-on-Chip Microwave Radiometer for Thermal Remote Sensing and its Application to the Forest Fire Detection

This paper focuses on the opportunities offered by the latest advances in silicon technologies for realizing system-on-chip microwave radiometer. Such a highly integrated, low-cost, radiometer chip could be applied to the environmental remote sensing and, in particular, to the forest fire detection. The feasibility study is carried-out in two steps. First, a proof of the concept is given by means of a discrete-component radiometer operating at 12.65GHz. This radiometer exploits SAT-TV components such as low-noise down-converter and dish antenna. On-field measurements shows a radiometric contrast (increase of the antenna noise temperature due to the fire with respect to the background) of about 8K for a wooden fire of 0.38 square meters placed 30m away from the antenna. Then, a single-chip 13GHz radiometer has been designed exploiting a CMOS 90nm standard process. The sensor is based on a direct-conversion architecture with integrated LNA, Gilbert cell mixer and PLL frequency synthesizer. The IF chain includes an active (gm-C) low-pass filter and a CMOS square-law detector. The circuit simulations show a total receiver gain of 72dB, an equivalent input noise temperature of 105K and an IF bandwidth of 100MHz.