A Low Phase Shift Step Attenuator Using p-i-n Diodes Switches

A fast S-band MIC highdynamic ranqe (0+70 dB) step attenuator is described, with a very small phase change versus attenuation levels. To obtain this, three similar two-paths sections are cascaded, each being able, by means of a couple of SPDT p-i-n diodes switches, to attenuate 0 dB or, respectively, 10, 20, and 40 dB. Experimental results are given, referring to a circuit breadboard operating from 2 to 4 GHz, the phase change being less than ~11/spl deg/ over all the octave band.