Rapid Calibration of Variable Gain Phase Shifters: A Novel Characterization Approach with Sparse Measurements

This paper introduces a new approach to characterize variable gain phase shifters (VGPSs), aiming to address the prolonged measurement time associated with the calibration of high-resolution VGPSs. The proposed method employs a judiciously chosen set of constellation states to capture the VGPS behavior. Subsequently, the acquired characterization dataset serves as the basis for the creation of six mapping functions, each elucidating a specific aspect of the VGPS response. These mapping functions are then harnessed to precisely determine the code words necessary to achieve a desired constellation, mitigating the need for exhaustive measurements. To validate the efficacy of the rapid calibration process, the proposed approach is implemented for calibrating a commercially available VGPS featuring an 8-bit phase resolution and 8-bit gain tuning resolution. Only 58 constellation states are needed for constructing the mapping functions and generating control code words. The outcome demonstrates the capability of achieving phase and gain root mean square errors of approximately 0.49 degrees and 0.15 dB, respectively.

I. Introduction

The significance of phased array technology remains paramount in 5G and satellite communications, providing a viable solution to the challenge of high path loss at millimeter-wave (mm-wave) frequencies and the pursuit of high Effective Isotropic Radiated Power (EIRP). Numerous Radio-Frequency (RF) beamforming designs, as reported in the literature [1]–[5], leverage Variable-Gain Phase-Shifters (VGPS) on each RF branch to shape the radiation pattern and steer the beam, as depicted in Fig. 1 [1]–[3], [6]–[9]. However, the non-negligible parasitics in both passive and active components implementing VGPSs, particularly at high operational frequencies, introduce gain and phase tuning errors.