Very compact high-gain broadband low-noise amplifier in InPHEMT technology

This paper presents the practical design methodology of an InP high electron-mobility transistor broadband low-noise amplifier (LNA) using multilayer transmission lines. The LNA consists of high-pass reactive matching circuits and resistive-feedback circuits in order to achieve both low-noise and broadband characteristics. The fabricated five-stage LNA successfully delivered a 43-dB gain with a noise figure of 1.9 dB at 23 GHz, and a gain of more than 40 dB from 18 to 43 GHz. The maximum gain was 49.5 dB at 32 GHz and the chip size was only 1.8 x 0.9 mm(2), resulting in a gain density of 30.5 dB/mm(2). To the best of our knowledge, this gain density is the highest performance in any Ka-band LNA reported to date. In addition, a more compact LNA using spiral inductors was also demonstrated.