A Commutated-<i>LC</i> RF Broadband Delay Circuit

This article presents a commutated-inductor–capacitor (commutated- $LC$ ) or switched- circuit that acts as radio frequency (RF) delay line. Thanks to its linear-periodically time-varying (LPTV) operation and fully passive implementation, it concurrently achieves long maximum delays, fine tuning steps, wide instantaneous bandwidths while being low loss highly linear. Unlike existing LPTV switched-capacitor broadband the introduction of inductors in proposed commutated- provides new degree freedom, allowing operate at much higher RF with wider bandwidth. A proof-of-concept prototype 65-nm CMOS process demonstrates measured 1.3-GHz 3-dB bandwidth around 4.3-GHz RF, i.e., 30% fractional bandwidth, when clocked 250 MHz. The is 1.4 ns 23-dB noise figure; this orders magnitude lower compared linear-time-invariant lines operating similar same delay. IIP3 +16 dBm.