A 2–15-GHz Accurate Built-in-Self-Test System for Wideband Phased Arrays Using Self-Correcting Eight-State $I/Q$ Mixers

A built-in-self-test (BIST) system for wideband phase arrays channels is presented. The BIST is implemented using an on-chip in-phase/quadrature (I/ Q) receiver with an integrated ring oscillator that provides both the channel test signal and the mixer local oscillator (LO). The BIST achieves wideband accuracy for relative phase and gain measurements at 2-15 GHz with a one-time self-correction algorithm with eight LO phases. The sequential algorithm determines the I/ Q errors, such as dc offset, gain and phase imbalances from the I/ Q outputs resulting from different LO phase states. An rms power detector network is also implemented for absolute gain measurements. The BIST can operate at rates >1 MHz (less than 1-μs sampling time) with signal-to-noise ratio greater than 50 dB and provides measurements that agree well with the vector network analyzer S-parameter data over a wide frequency range. To the best of our knowledge, this is the first implementation of high accuracy wideband BIST system for phased-array channels.