A 94-GHz 6-bit High-Precision Phase Shifter Based on Dual-Injection Gilbert Vector Modulator

This article presents a 94-GHz 6-bit high-precision phase shifter based on a dual-injection Gilbert vector modulator (DIG-VM). It is composed of two polarity switching amplifiers (PSAs), an I/Q signal generator, and a DIG-VM. The proposed DIG-VM not only maintains a constant input impedance in all phase states, thus suppressing the loading effect of the I/Q signal generator but also reduces the maximum errors caused by I/Q signal mismatches. Theoretical analysis shows that the maximum phase error due to I/Q signal phase mismatch and the maximum gain error due to I/Q signal magnitude mismatch are only half of those in the conventional Gilbert VM. In addition, the 90° PSA and 180° PSA are designed to complete the 360° phase shift and provide additional gain. The proposed phase shifter is fabricated using 0.13-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m SiGe BiCMOS process with a core area of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$750\times 450~\mu $ </tex-math></inline-formula>m. The measured results show that the proposed phase shifter achieves an rms gain error of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.58\sim 0.85$ </tex-math></inline-formula> dB and an rms phase error of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.2^{\circ }\sim 2.9^{\circ }$ </tex-math></inline-formula> across <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$91.5\sim 98$ </tex-math></inline-formula> GHz. In addition, the peak average gain reaches 14.4 dB at 94.5 GHz and the input 1-dB compression point is −14 dBm at 94 GHz.