Benchmarking a High Electron Mobility Transistor Using an Active Load-Pull System at 120 GHz–170 GHz

This study presents an in-depth investigation into the high-frequency capabilities of a commercial 100 nm InP high electron mobility transistor (HEMT) through small and large signal analysis. The report centres on the analysis of output power, gain, and power-added efficiency (PAE), aiming to provide an accurate and comprehensive evaluation of device performance. Initially, the DC characteristics of the test transistor are examined to ascertain the optimal operating point. The large-signal performance is conducted in non-50 Ω impedance conditions, employing active load-pull measurements up to 170 GHz. The obtained measurement results reveal that the transistor achieves a gain surpassing 0.5 dB at 170 GHz in a 50 Ω S-parameter measurement system, however, the subsequent non-50 Ω measurements show a PAE of 6.5 % and a gain of 3.5 dB at 170 GHz. These values are in good agreement with numerical modelling results. These findings have revealed the true potential of these devices.

I. Introduction

The demand for high data transmission rates in wireless and mobile communications and high resolution in radar drives the carrier frequency to the higher millimeter-wave (mm-wave) range i.e., beyond 100 GHz [1] – [4] . Challenges loom for designers as the intricacy of component manufacturing escalates with frequency, while shorter wavelengths necessitate smaller component sizes. For example, as the core components in the front end of those systems, amplifiers suffer from low gain, low output power, and low efficiency at those frequencies. New transistor technologies or new designs based on the existing transistor technologies, e.g., optimizing circuit design to enhance gain, output power, and efficiency, have become a compelling priority. This pursuit of optimal circuit design mandates sophisticated device models or comprehensive transistor characterisation.