W-band finite ground coplanar monolithic multipliers

This paper describes the design, fabrication, and experimental evaluation o f W-band planar monolithic varactor frequency multipliers based on finite g round coplanar (FGC) lines. These lines are a low-loss low-dispersion alter native of a planar transmission line to more conventional microstrip or cop lanar waveguide lines at millimeter-wave frequencies. The near transverse-e lectromagnetic nature of propagation of the FGC lines simplifies circuit de sign and layout. Two-diode W-band varactor multipliers with input Q's of tw o and three and FGC input and output have been realized. The multiplier wit h input Q = 2 has an output power of 72 mW, an efficiency of 16.3% near 80 GHz, and a -3-dB bandwidth greater than 10 GHz, while the multiplier with Q = 3 has an efficiency of 21.5% near 70 GHz and a 6-GHz bandwidth. This pap er will briefly describe the characteristics of the FGC lines, the design o f the multipliers, and their radio-frequency performance.