A MONOLITHIC HEMT PASSIVE SWITCH WITH INTEGRATED HBT STANDARD LOGIC COMPATIBLE DRIVER FOR PHASED-ARRAY APPLICATIONS

We have achieved the first demonstration of a monolithically integrate d high electron mobility transistor (HEMT) passive switch with a heter ojunction bipolar transistor (HBT) switch-driver circuit that represen ts key integrated mixed-signal functions. The HEMT-HBT monolithic micr owave integrated circuit (MMIC) is fabricated using selective molecula r beam epitaxy (MBE). The single HEMT series switch is driven by an HB T circuit that provides both level shifting and wide voltage drive swi ng to adequately turn the passive HEMT switch device on and off The MM IC can be made compatible for operation from either standard TTL or CM OS control signals. The series 0.2 x 200 mu m(2) passive HEMT switch a chieves 1.6-2.9 dB insertion loss over a 50 MHz to 12 GHz band when th e HEMT is turned on. The corresponding return-losses are >10 dB across the band. When the switch is turned off, the isolation ranges from >4 0 dB at 1 GHz and decreases to 15 dB at 12 GHz. This integrated HEMT s witch and HBT switch driver MMIC represents a basic building block tha t can be applied to programmable phase shifters used in phased-array a ntenna applications and can result in a dramatic reduction in size and improvement in performance of these systems.