HEMT Control Circuits for Monolithic InP Applications

InAlAs/InGaAs HEMT control circuits are studied for monolithic InP applications. Experimental characteristics are presented for bridged-, T-and ¿-topologies. Best performance is obtained for single-cell ¿-attenuators. (DC to 26.5 GHz with 30 dB dynamic range and ¿19 dB return loss). These excellent broadband characteristics benefit from the high electron mobility of the devices. Less than 1 nsec switching times were measured. Small-signal characteristics of the ¿-attenuator were maintained up to input-powers of about 11 dBm at 5 GHz. The technology merits and suitability for very high frequency applications are discussed.