IF Amplifier Section in 90 nm CMOS Technology for SoC Microwave Radiometers

In this letter a novel design solution in 90 nm CMOS technology is proposed for the IF amplifier, low-pass filter and square-law power detector of a system-on-chip (SoC) microwave radiometer. To minimize the number of off-chip components (just a single capacitor) the IF filter is based on an active g_mC configuration, whereas the power detector exploits the MOS transistor non-linearity, i.e., avoiding the need for Schottky diodes. The fabricated IF chip features a sensitivity of 3 mV/nW, a linearity range of about 25 dB around the -60 dBm level, a noise equivalent bandwidth of 58 MHz and a current consumption of only 1.8 mA at 1.2 V supply. The core area is within a rectangle of 220 mum times 540 mum. The proposed design solution is also compatible with SiGe BiCMOS processes and can be regarded as a further step toward the realization of microwave radiometric sensors fully integrated on silicon.