220-GHz metamorphic HEMT amplifier MMICs for high-resolution imaging applications

In this paper, the development of 220-GHz low-noise amplifier (LNA) MMICs for use in high-resolution active and passive millimeter-wave imaging systems is presented. The amplifier circuits have been realized using a well-proven 0.1-mu m gate length and an advanced 0.05-mu m gate length InAlAs/InGaAs based depletion-type metamorphic high electron mobility transistor technology. Furthermore, coplanar circuit topology in combination with cascode transistors was applied, leading to a compact chip size and an excellent gain performance at high millimeter-wave frequencies. A realized single-stage 0.05-mu m cascode LNA exhibited a small-signal gain of 10 dB at 222 GHz, while a 0.1-mu m four-stage amplifier circuit achieved a linear gain of 20 dB at the frequency of operation and more than 10 dB over the bandwidth from 180 to 225 GHz.