Design and analysis of a tunable broadband 180‐degree active coupler with low phase‐error and high‐directivity using staggering technique

This study presents the design and analysis of a 180° tunable non-reciprocal active broadband coupler. To increase bandwidth, multi-section impedance transformation technique is utilised. The coupler includes two amplifiers, three filters (phase-shifters) on gate (drain) line, referred to as through-path (coupled-path). achieve an accurate coupler, staggering utilised for designing filters. Lumped-element analysis, adopted here first time analyse reveals impacts each element directivity, output phase-shift, phase-error. post-layout simulation are performed in 0.18 µm CMOS technology over frequency range 10–20 GHz. An phase ± 1.7°, directivity more than 27 dB, return loss better 10 dB achieved. coupling gain 7.7 at centre frequency, noise figure 4.8 power consumption 22 mW. By tuning bias voltage, imbalance caused by process variations can be compensated. Also, prototype was fabricated tested Rogers substrate 8–10 GHz band, giving 2° >15 dB.