An ultra-wideband variable gain low noise amplifier

This paper presents an ultra-wideband variable gain low noise amplifier (UWB-VGLNA). At the input stage, a common-emitter and common-base amplifier with serial-parallel feedback network and active bias network was used to achieve good wideband input impedance matching. At gain-tuning stage, a combinational circuit consisting of active inductor load and Darlington cascode amplifier with gain tuning transistor was employed to not only realize the tunable output gain, but also increase gain and achieve greater gain tunable range. At the output stage, a common-collector amplifier with tunable current mirror was designed to achieve good wideband output impedance matching and extend gain-tuning range. The UWB-VGLNA is designed based on the standard WIN 0.2μm GaAs HBT process. The UWB-VGLNA showed S
₂₁
tunable range from 8.7dB to 29.1dB; the S
₁₁
of less than -10dB; the S
₂₂
of less than -11dB; the NF of less than 4.3dB; the stability coefficient (Mu1) of over 3. The static power consumption is less than 34mW under the operation voltage of 4 V.