A novel 3-D integrated RTD-HFET frequency multiplier

A frequency multiplier circuit using a resonant tunneling diode (RTD) as a load of a HFET is developed. Based on 3D-monolithic integration on a semi-insulating InP-substrate, a demonstrator is realised generating odd higher harmonics with high efficiency. The multiplier is highly compact and combines amplification of the fundamental frequency in the HFET with the high switching performance of the RTD. The Microwave Design System is used to evaluate its ultra high frequency potential predicting 0.115 times the voltage amplitude of the fundamental input signal for the third harmonic at 100 GHz. Optimization of the circuit design and the RTD-layer structure on top of the HFET with respect to the peak and valley parameters will increase the efficiency.