Design of Broadband Digital Variable Gain Amplifier

The DVGA is based on 0.18μm SiGe BiCMOS process and integrated modules such as Mode Switch, Gain Control, Output Stage, Input & Output Interface and so on. In order to meet the requirements of broadband communication, the DVGA uses folded cascode as active negative feedback to pull down the node impedance and achieve a bandwidth of 1.26GHz. The circuit has a gain range of 61dB, OP1dB of 18dBm, NF of 6dB and CMRR of 88dB. It is suitable for high-speed broadband RF front-ends.