Low Cost DC to 6 GHz Electronic Step Attenuator SMT MCMs with Gate Lag Elimination By Use of High Intensity LEDs

Output step attenuators for microwave test instrumentation are continually being pushed to perform faster, more reliably, with lower loss and less distortion, and at lower cost. This paper describes a state of the art GaAs FET switch IC based, high dynamic range step attenuator topology using SMT MCMs operating from DC to 6 GHz that has low loss, low distortion, fast switching speed with minimized transients, and low cost. These modules use light from high intensity LEDs reflected off of the package lid in a novel, low cost manner to provide compact, inexpensive elimination of the gate lag effect commonly associated with GaAs FET based switching, such that this attenuator provides an amplitude stable output within 20 mus of when a change of attenuation state is initiated. This is the first reported usage of light from LEDs reflected off of the lid of an MCM SMT package to eliminate the gate lag effect in a GaAs FET switch based subsystem