A Novel HBT Frequency Doubler Design for Millimeter-Wave Applications

In this paper we present a novel HBT frequency doubler design for millimeter-wave application. HBT frequency doubler theory is described which leads to accurate design equations for improved performance. The developed theory shows that a substantial improvement in the HBT frequency doubler operation can be achieved using a novel second harmonic feedback network. Preliminary measurements on a frequency doubler implemented in a high-speed InP DHBT technology demonstrates an increase in the maximum output power from -14 dBm to -11.5 dBm at an input frequency of 31.4 GHz due to the presence of the second harmonic feedback network. We demonstrate here that the 3 dB improvement in performance is directly due to the feedback mechanism