CM-Wave Modulator with High-Voltage 4H SiC pin Diodes
The results of mathematical simulation, development and investigation of a modulator with 4H SiC pin diodes are presented. We simulated the effect of bias modes on isolation and transmission between the modulator input and output in the 1−20 GHz frequency range, for pin diodes with 6 μm long i-region. It was calculated that the isolation in a modulator with three diodes may run into –45 dB, the transmission losses being no more than 2 dB. The modulator was made as an integrated circuit (IC) on the basis of nonsymmetrical strip lines (characteristic impedance of 50 Ω) incorporating chips of high-voltage 4H SiC pin diodes with iregion 6 μm long, mesa diameter of 60 μm and calculated avalanche breakdown voltage of 1000 V. We studied the experimental parameters of this modulator as a function of forward current and reverse voltage in the 2.4−12 GHz frequency range, as well as the microwave signal switching behavior. It was determined that the modulator is characterized by transmission losses of 1.0−2.0 dB and isolation of 27−34 dB (in the 2.4−7 GHz frequency range). The formation of microwave pulses with leading (trailing) edge of 22 (29) ns was also observed.
Robert P. Devaty, David J. Larkin and Stephen E. Saddow
M. S. Boltovets et al., "CM-Wave Modulator with High-Voltage 4H SiC pin Diodes", Materials Science Forum, Vols. 527-529, pp. 1379-1383, 2006