A 25.1-27.6 GHz Tunable-Narrowband Digitally-Calibrated Merged LNA-Vector Modulator for 5G Phased Arrays

This paper presents a compact differential quadrature generation scheme using transformer coupled-resonators for use in scalable 5G phased-array architectures. In this work, quadrature generation is seamlessly integrated with the load of an LNA gain stage, thus obviating the need for an explicit quadrature hybrid in the vector modulator. A 25.1-to-27.6 GHz phased array channel employing the proposed scheme is implemented in 65 nm CMOS. The merged LNA-vector modulator is demonstrated to be digitally tunable across 2.5 GHz, and achieved greater than 430 MHz bandwidth (quadrature error ≤ ±6.4°), small RMS phase error (≤ 2.6°), while occupying a composite area of only 0.123 mm
²
. An on-chip calibration scheme to achieve quadrature locking at a desired frequency is also presented.