Ultra-Wideband 6-Bit Passive Phase Shifter with Open-Circuit Microstrip Pseudo-π Network and Low RMS Phase Error

This study presents an ultra-wideband (UWB) 6-bit passive phase shifter (PS) with low root-mean-square (RMS) phase error in 0.25-µm GaAs technology. By adopting the open-circuit microstrip pseudo-π network (OMPN), the proposed PS achieves a low RMS phase error over a wide fractional bandwidth (FBW). The phase accuracy is improved by optimizing the characteristic impedance of the microstrip lines in the OMPN. The proposed UWB 6-bit passive PS covers 360◦ with a 5.625° resolution over 5.5-18.1 GHz. Measurements indicate that the RMS phase error is below 3° at the 108% fractional bandwidth (FBW). The average insertion loss (IL) is 13 ± 2 dB with an RMS amplitude error of less than 1.1 dB. The IP1 dB is about 23 dBm. The chip area, including all pads, switch driver, DC, and RF routing, is 3.6 mm × 3.6 mm.