X-band and Ka-band monolithic GaAs PIN diode variable attenuation limiters

A description is given of monolithic GaAs p-i-n diode limiter circuits that have demonstrated 20 dB of variable attenuation at X-band and Ka-band while maintaining under 1.5:1 input voltage standing-wave ratio (VSWR). Insertion loss is 0.5-dB at 10 GHz and 1.4-dB at 36.5 GHz in the 0-mA bias condition. Passive limiting provides 7-dB of isolation at radio frequency (RF) powers up to 1.5 W (30% duty cycle). The process used to fabricate the variable attenuation limiter is compatible with FET circuits, allowing integration of other MMIC components on the same substrate for future single-chip radar front ends. Several of these circuits have been fabricated and RF tested. Fabrication, circuit design, and RF performance are discussed.<>