A novel wideband MMIC voltage controlled attenuator with a bandpass filter topology

The design and analysis of a novel wideband, monolithic, bandpass, /spl pi/-network, voltage controlled attenuator (VCA) is presented. A 24 to 32 GHz VCA was developed using 0.15 /spl mu/m GaAs pHEMT technology. This is the first reported VCA to use a bandpass filter topology to achieve the required operating frequency band and eliminate the effects of parasitic capacitances of the pHEMTs. The bandpass filter absorbs the parasitic capacitances and thereby eliminates their detrimental effects. The measured attenuation dynamic range is 12 dB /spl plusmn/ 0.5 dB with minimum insertion loss of 2-3 dB. The input power handling capability is up to 0 dBm. The VCA is well matched and may be placed in a 50 /spl Omega/ system (S.M. Halabi, 2004).