Two-octave digital all-pass phase shifters for phased array applications

Wideband Digital phase shifters with two octaves bandwidth and phase shifts of 180° and 90° from 600 MHz to 2400 MHz based on All-Pass Networks (APN) are presented. Ideally, this type of phase shifters has extremely good wideband performance. Practically, however, it is difficult to achieve due to the performance variance of the large number of required discrete components. For the first time, this problem is addressed by performing a Monte Carlo analysis to identify the main sensitivities. For validation, four 2-bit phase shifters are realized with the most critical components tuned, based on the analysis. A return loss larger than 10 dB, maximum phase error of ±5.8°, ±3.6° and ±8.8° for phase shifts of 90°, 180° and 270° are consistently obtained in all the realizations.