A high linearity digital attenuator with low phase variations for X-band phased array systems

A 6 bit high linearity digital attenuator with low phase variations for X-band phased array systems is presented, the phase variation and linearity of conventional switched Pi attenuators is analyzed in detail. By using the inductive and capacitive compensation, the attenuator can be realized with low phase variation at different attenuation states in a broadband frequency range. In additional, the floating substrate technique was used to acquire high linearity. The attenuator was fabricated by 0.13um BiCMOS process. The simulation results of the proposed attenuator achieves 6.67dB insert loss, the input 1dB compression point at minimum attenuation and maximum attenuation is 15.5dBm and 21dBm at 10 GHz, respectively.