A systematic coupling balance scheme to enhance amplitude and phase matches for long traveling multi-phase signals

This paper presents a systematic coupling balance technique to enhance signal matches for long traveling N-pair differential signals. The analysis is conducted on 2N lines with closed-form expressions to indicate the three causes of mismatches. Then, a systematic method is presented to address the three factors to realize balanced coupling for signal matches by using twisting schemes. The effectiveness of this technique is demonstrated on FR4 printed-circuit board (PCB) for I Q traces, which shows great suppression of I Q imbalances with well-matched simulation and measurement results. The bandwidth with 1° mismatch is boosted from 75MHz to 360MHz, or from 135MHz to 680MHz considering the overall effects of the four signals. This technique requires no power consumption or complex circuits or algorithms, and can be extended to high frequencies with the scaling of the structure size.