A 22.5~28.5 -GHz Low-Amplitude-Variation Low-Phase-Error Hybrid Phase Shifter Using Flatness Enhancement Techniques for 5G NR in 40-nm CMOS

This brief presents a hybrid phase shifter (PS) that integrates a three-stage switch-type phase shifter (STPS) and a one-stage reflect-type phase shifter (RTPS). The STPS utilizes a flatness-enhanced $\pi $ -network topology to reduce phase error and insertion loss (IL) variation by eliminating feedback and resonant capacitors. The RTPS enables continuous phase shifting with a 4-bit capacitor array and varactor. The proposed hybrid PS achieves an IL variation of ±0.7 dB and an RMS phase error of 0.3° to 1.2° in the $22.5\sim 28$ .5 GHz range. Compared to existing designs, the hybrid PS offers superior performance in phase accuracy, IL variation, and area efficiency, with a compact area of $151\times 342~\mathrm {\mu } m^{2}$ , fabricated using standard 40nm CMOS technology.