CMOS Distributed Amplifiers With Extended Flat Bandwidth and Improved Input Matching Using Gate Line With Coupled Inductors

This paper presents a state-of-the-art distributed amplifier with coupled inductors in the gate line. The proposed coupled inductors, in conjunction with series-peaking inductors in cascode gain stages, provide bandwidth extension with flat gain response for the amplifier without any additional power consumption. On the other hand, gate-inductor coupling improves the input matching of the amplifier considerably. The detailed analysis and design methodology for the proposed distributed amplifier are presented. The new four-stage distributed amplifier, fabricated using an IBM 0.18-??m complementary-metal-oxide-semiconductor process, achieves a power gain of around 10 dB, input and output return losses better than 16 and 18 dB, respectively, a noise figure of 3.6-4.9 dB, and a power consumption of 21 mW over a 16-GHz flat 1-dB bandwidth. The measured IIP₃ of the amplifier is between 0.1 and 3.75 dBm across the entire band.