Predicting nonlinear electrical performance in single and multiple quantum-barrier varactors (QBV's) by the Monte Carlo technique

In this paper, nonlinear characterization and simulation of single and multiple quantum barrier varactors (QBV's) are obtained by using a multiparticle Monte Carlo simulator. The I-V relation is deduced directly from the equivalent charge variation and the bias voltage. The C-V characteristics are simply calculated from the width of the depletion region in a similar manner as for a parallel plate capacitor. The RF behavior is also simulated by modulating the voltage at 50 GHz and by performing an FFT of the current to study higher harmonic content of the QBV's. It is observed that only odd harmonics are generated and the current level of the third harmonic is about 10% of the injected signal current level. It is also shown that the use of multistack barriers can reduce the current density and the capacitance in accordance with the number of barriers in addition to increasing the breakdown voltage.