A 6-bit Active Phase Shifter for X- and Ku-band Phased Arrays

Abstract

This paper presents a 6-18 GHz active 6-bit phase shifter based on a vector-sum technique in $0.13-\mu m$ SiGe BiCMOS technology for X- and Ku-band phased arrays. An input Marchand balun and an L-C resonance-based quadrature all-pass filter are used to generate two orthogonal vectors with high $I/Q$ accuracy and high linearity over a wide frequency band. The $I/Q$ reference signals are then fed into two VGAs, of which the gains are adjusted with an integrated current-mode DAC to achieve the 6-bit phase resolution between $0-360^{o}$. The phase shifter shows 3.12 $dB$ of power gain at 9.25 GHz with a 3-dB gain bandwidth of 6.4-12.9 GHz, and the RMS gain variation is $\lt 1.05 dB$ for all 6-bit phase states. The phase shifter achieves an input P1dB of $5-8dBm$ at 6-18 GHz for 0°-phase state. The measured RMS phase error is $\lt 5.6^{o}$ at 5-18 GHz. The total current consumption is 28.2 $mA$ from a 3.3 V supply voltage and the overall chip size is $1.85\times 1.32mm^{2}.$