A Broadband LNA With Multiple Bandwidth Enhancement Techniques

This letter presents a broadband multistage low-noise amplifier (LNA) in a 0.15-
$\mu \text{m}$
GaAs pseudomorphic high-electron-mobility (pHEMT) process. The LNA employs multiple bandwidth extension techniques, including cascode, feedback, and gain-enhanced source–drain coupled line (SDCL). The SDCL enhances the gain by combining the source and drain signals and compensates the gain roll-off of the amplifier, which is first proposed in this letter to our knowledge. These techniques are adopted in a three-stage monolithic microwave integrated circuit (MMIC) LNA, achieving a wide bandwidth with high gain. The measured results show that the LNA obtains an average gain of 24.7 dB and a noise figure (NF) of 1.7–2.8 dB in 0.5–24 GHz, with a compact chip area of only 1.47 mm2.