SiGe BiCMOS high-gain and wideband differential intermediate frequency amplifier for W-band passive imaging single-chip receivers

This study presents the results of a high-gain and wideband differential intermediate frequency (IF) amplifier circuit design for a W-band passive imaging single-chip (down-conversion) receiver front-end. The cascaded two-stage IF amplifier was fabricated in a 0.13 μm SiGe BiCMOS process technology with 300 GHz/500 GHz f_T/f_max. In total six on-chip inductors are used in the input, output and inter-stage matching networks which enable relatively broadband RF properties together with a compact circuit size for the IF amplifier (the die area is 0.27 mm² incl. RF and DC pads). The broadband SiGe amplifier has a measured gain of 10-19.5 dB at 2-37 GHz (|s₁₁| and |s₂₂| ≤ -10 dB at 7-40 GHz and 8-35 GHz, respectively), noise figure of 6.3-8.0 dB at 2-26 GHz and output third order intercept points of 7-17 dBm at 1-40 GHz (the DC power consumption is 122 mW). To the authors´ best knowledge, this work reports a first-time realisation of a differential IF amplifier made in a 0.13 μm SiGe BiCMOS technology that achieves such wideband impedance matching together with a high gain and reasonably low noise properties over a wide instantaneous bandwidth (|s₂₁| = 15-19.5 dB at 3-26 GHz).