High-cutoff-frequency gallium-arsenide diffused-junction varactor diodes

Device characteristics of GaAs diffused-junction varactor diodes are discussed. The maximum cutoff frequency (at breakdown voltage) is greater than 500,000 megacycles, and the breakdown voltage is as high as 20 volts. Junction capacitances from 0.1 to 1 micromicrofarad at -1 volt have been obtained, and a minimum dissipative resistance value of 0.8 ohm has been measured at 2000 megacycles. The design considerations for which the exponent, n, in the capacitance-voltage relation is between 0.4 to 0.5 are discussed. The geometry of the diode, the packages employed, and their electrical characteristics are presented. These packages exhibit the lowest capacitance in conjunction with lowest inductance of any package available.