X-Band 5-bit MMIC Digital Attenuator with Low Phase Shift

This paper presents the x-band 5-bit MMIC digital attenuator with low phase shift. Phase compensation techniques were used in the MMIC design to reduce the phase shift. This attenuator is fabricated with 0.2μm GaAs PHEMT process. Measurement results of the developed MMIC chips in the xband show that the 5-bit MMIC digital attenuator has 0.5dB resolution and 15.5dB dynamic attenuation range, input return losses was less than 10dB and output return losses was less than 13dB for all attenuation states, RMS is less than 0.2dB; insertion loss is less than 3.8dB; phase shift error is less than 5°for 35 attenuation states; The MMIC chip size is 1.58 mm×2.95 mm×0.1mm.