On the design and modelling of novel 3-D integrated RTD/HBT device frequency multiplier circuits

A RTD/HBT combination acting as a frequency multiplier is studied, both numerically and experimentally. The DC and quasi-static characteristic of the module are modelled using the HP MDS circuit simulator software based on measured characteristics of the individual devices. In presence of a non-linear, negative differential type feedback due to the RTD a precise DC-characterisation is obtained for a voltage controlled input as a function of bias, input voltage, and load resistance. While a full AC-analysis is pending a quasi-static description of the output spectrum was carried out. A demonstrator module is realised on s.i. InP using hybrid epitaxy with MOVPE (HBT) and MBE (RTD). The DC-characteristics are in full agreement with the calculated behaviour and allow a precise understanding of the complicated multiplication function. The quasi-static characteristics are proven by low-frequency multiplication measurements.