An Inductorless 6-GHz Variable Gain Differential Transimpedance Amplifier in 0.18-μm SiGe BiCMOS

This paper presents a new inductorless 6-GHz variable gain differential transimpedance amplifier (VGDTIA) with voltage bias controlled variable gain designed using TowerJazz 0.18-μm SiGe BiCMOS technology (using CMOS only). It consists of a modified cross-coupled regulated cascode preamplifier stage (CCRGC) and a cascaded amplifier stage with bias-controlled gain-variation and third-order interleaving feedback (CVG3F). The design has a transimpedance gain range of 20.6-60.5 dBΩ with constant bandwidth of 6.6 GHz and a dynamic range of 41.2 μA to 1.1 mA. The power consumption is 33.9 mW from 1.8 V supply, and the input referred noise current is 10.4 pA/√Hz. This design is compact and the core area is 100 μm × 85 μm.