A Low-Loss, Compact Wideband True-Time-Delay Line for Sub-6GHz Applications Using N - Path Filters

N-path switched-capacitor (SC) based realization of integrated passive true-time-delay (TTD) lines at RF frequencies are highly attractive in terms of delay bandwidth (DBW) product, area, and power consumption. However, the inherent low-pass nature of capacitor response limits the efficacy of these designs at higher RF frequencies. The introduction of an inductor in the N-path SC circuit facilitates its effectiveness at considerably higher RF frequencies with wider instantaneous bandwidth (BW). This work presents a two-inductor 8-path SC all-passive compact low-loss RF delay element offering gigahertz(GHz)-wide instantaneous BW and nanosecond-scale delays with simultaneous clock-path-defined delay tuning, at sub-6G Hz RF. The proposed architecture substantially reduces the chip area and insertion loss (IL), while preserving the linearity owing to its all-passive nature. Additionally, it decouples the clock-path-controlled delay settings and delay-line (DL) losses. Simulation results show
$\approx 1.6\text{ns}$
delay over an instantaneous 3-dB BW of 2.5GHz centered around 4.5GHz RF, resulting in DBW product of 4, outperforming the state-of-the-art DL architectures.