A Tunable SiGe BiCMOS Gain-Equalizer For X-Band Phased-Array RADAR Applications

This brief presents a compact-size tunable gain-equalizer for X-band phased-array RADAR applications in a 0.25-μm SiGe BiCMOS technology. An isolated nMOS-based variable resistance was used for the first time to tune the slope of the gain-equalizer. For nMOS, an isolated body created by a deep n-well was utilized to reduce insertion loss due to the substrate conductivity. Furthermore, the power-handling capability of the tunable gain-equalizer was improved thanks to the resistive body-floating technique. The designed tunable gain-equalizer operates in the frequency range from 8 to 12.5 GHz with a measured positive slope of 1 dB/GHz and 1 dB tunable slope. The effective chip area excluding the pads is 0.21 mm
²
, and the total area including pads is 0.31 mm
²
. To authors best knowledge, this brief is the first tunable gain-equalizer in SiGe technology presented for X-band phased-array RADAR applications.