Sequential Loopback Built-in Self-Test Algorithm for Dual-Polarization Millimeter-Wave Phased-Array Transceivers

This paper presents a built-in self-test (BIST) algorithm for dual-polarization millimeter-wave beamforming transceivers. The proposed algorithm provides simplified loopback paths that can be implemented with short and equi length interconnections between neighboring transmitters and receivers. End-to-end channel response measurements for all neighboring loopback paths enable us to extract the all relative complex channel responses to a reference channel. Verification of the proposed algorithm was conducted in a test setup with the 5G millimeter-wave communications chipset boards. Compared to the reference 1-by-1 measurements, the measured gain and phase rms errors of the proposed scheme were 0.4 dB, 2.8° for the Tx and 0.6 dB, 3.9° for the Rx. After the calibration, large phase deviation between channels were successfully reduced from 15.2° and 42.1° to 4.9° and 4.4° for the Tx and Rx, respectively, which is comparable to the accuracy limit due to the on-chip phase shifters.