A broadband high dynamic range voltage controlled attenuator MMIC with IIP3 > +47dBm over entire 30dB analog control range

In this paper we introduce a novel design technique for broadband high dynamic range absorptive voltage controlled attenuators (VCA) on SOI CMOS. The VCA design is based on the classical passive FET `Pi´ and `Tee´ attenuator structures but uses stacked FET techniques to dramatically improve the signal handling capability. The VCA has >;30dB attenuation range over a frequency band from DC to >; 5GHz and achieves an IIP3 of >; +47dBm over the entire analog control range. The use of a stacked FET structure evenly distributes the RF signal across `N´ FET devices thus reducing the 3rd order distortion generated by each individual FET. The reduction in distortion gained is directly proportional to the degree of stacking used.