68–110-GHz-Band Low-Noise Amplifier Using Current Reuse Topology

This paper proposes a new topology for a broadband low-noise-amplifier (LNA). A common-gate (CG) amplifier with a matching inductor composes a unit cell, and the unit cells are cascaded to increase gain. As both the input and output impedances of the unit cell are matched to 50 Ω for a wide frequency range, it is possible to increase the gain while maintaining wide bandwidth. Thus, high-gain and broadband performance can be obtained using this topology. The other features of the amplifier are its small size, low power consumption, and current reuse topology. This paper presents the design methodology of a multistage CG amplifier with a matching inductor. Fabricated in an 80-nm InP HEMT process, we developed an ultra-broadband LNA. The LNA with a three-stage CG amplifier exhibited a gain of 18 dB and a noise figure of 3.5 dB from 68 to over 110 GHz. The power consumption was 12 mW under a power supply voltage of 3 V. The chip size is 0.55 × 0.75 mm². Furthermore, we developed a receiver for passive millimeter-wave imagers by integrating a six-stage LNA with a power detector. The chip size of the receiver is 1.1 × 0.75 mm². The sensitivity of the pre-amplified detector was more than 2 000 V/mW from 75 to 100 GHz. These results show that the topology is one of the best candidates for high-gain and broadband LNA with small size and low power consumption.