Microwave Modulators Based on 4H-SiC p-i-n Diodes

Multidiode broadband microwave signal modulators based on 4H-SiC p-i-n diodes were fabricated and fully characterized for the first time. The diodes used for the modulator fabrication exhibited a blocking voltage of 1100 V, a 100-mA differential resistance of 1-3 Omega, a punch-through voltage (100 V) capacitance below 0.5 pF, and a carrier effective lifetime of 15 ns. The three-diode modulators are characterized by a transmission loss of 1-2 dB and isolation of 27-34 dB in the 2-7-GHz frequency range, while their switching speed is as low as 30 ns. Two-diode modulators were specially designed for high-temperature operation. These modulators are characterized by a transmission loss of 1.1-2.6 dB and isolation of 33-44.5 dB in the 2-7-GHz frequency range at temperatures up to 300degC.