UHiFET – A New High-Frequency High-Voltage Device

The HiFET (High-Impedance, High-Voltage FET) configuration is used to connect several semiconductor FETs both DC and RF in series, resulting in high DC bias voltage and high output impedance. The HiFET power and efficiency degrades at high microwave frequencies (i.e. > 3GHz) due to gate leakage currents. In this article, we propose a new configuration, the Universal HiFET (UHiFET), which uses an additional compensation to equalize the RF voltages and currents of all the transistor cells that are connected in series. This new approach improves the power, efficiency and linearity of the original HiFET configuration at microwave and millimeter wave frequencies. We are presenting a mathematical analysis of the UHiFET and measured data to demonstrate the effectiveness of the proposed approach.

Index Terms — Broadband amplifiers, high-voltage techniques, microwave devices, power combiners, MMICs.

Final Paper _IMS2011_.pdf