Dynamic Base Current Compensation for Cascaded Bipolar Low Noise Amplifier

Abstract

Scientific instruments often need an electronic readout system with small input noise, large output signals and small distortion. In order to adapt the newest requirements of an X-ray space mission, several differential low-noise amplifiers have been developed employing diodes as loads, based on a 350 nm SiGe BiCMOS technology. The amplifiers have shown a good performance of AC gain, noise and gain- drift. However, the linearity degrades due to cascaded topology. This work proposes a new design with a dynamic base current compensation system based on the original amplifier topology, appended to the cascaded differential pairs using diodes as loads. The linearity performance is strongly improved according to the dedicated simulation results. The mismatch issue has been further verified by Monte-Carlo simulations.

Keywords

• non-linearity
• low-noise amplifier
• differential amplifier
• bicmos technology
• hetero-junction bipolar transistor