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 12.65 GHz. This radiometer exploits TV-SAT 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 8 K for a wooden fire of 0.38 m 2 placed 30 m away from the antenna. Then, a single-chip 13 GHz radiometer has been designed exploiting a CMOS 90 nm standard process. The sensor is based on a direct-conversion architecture with integrated LNA, Gilbertpsilas 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 72 dB, an equivalent input noise temperature of 105 K and an IF bandwidth of 100 MHz.