A 20–36-GHz Voltage-Controlled Analog Distributed Attenuator With a Wide Attenuation Range and Low Phase Imbalance
Bosung Suh, Byung‐Wook Min
Abstract
A K-/Ka-band distributed attenuator in a 28-nm CMOS process is presented for a phased array. The proposed voltage-controlled distributed attenuator is designed using nonuniform varistors for a wide attenuation range with a compact size. An attenuation range of 25 dB was achieved with only three sections, which are 90° apart. The phase imbalance of the proposed attenuator is minimized using an artificial quarter-wave transmission line with series-connected varistors. The measured insertion loss of the proposed attenuator is 1.6-2.5 dB from 20 to 36 GHz. The insertion phase imbalance is less than 10° within the same bandwidth. The input 1-dB compression point is 10.6 dBm (defined as the 1-dB drop in the maximum attenuation range) at 28 GHz. The total chip size, including pads, is 0.77 × 0.42 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The proposed attenuator has the highest attenuation range relative to the chip area compared with previously distributed attenuators.