An E-band Subradix Active Phase Shifter With < 0.69° RMS Phase Error and 16-dB Attenuation in 28-nm CMOS

Abstract

This paper proposes an E-band active phase shifter, which leverages a subradix-2 gm array to achieve low gain and phase errors. The phase shifter stacks differential couplers for high precision quadrature signals. It employs extensive (2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> ) vector modulation control states provided by the subradix-2 arrangement for high accuracy that is not available in conventional vector modulation (VM) based phase shifters. The proposed E-band phase shifter is fabricated in 28-nm CMOS with a chip area of 0.078 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . It provides a 5.625° phase accuracy with root mean square (RMS) phase error of 0.38~0.69°, and RMS gain error of 0.49~0.83 dB at 67–79 GHz. In addition, the phase shifter supports 16 dB attenuation range with a 2 dB step. Measurements show it can also provide a 1.4° phase accuracy with RMS phase error of less than 0.77°. The phase shifter consumes 28.5 mW from a 1.2 V supply.