Low loss negative group delay circuit using self‐packaged suspended line

Abstract

A matched negative group delay (NGD) circuit with ultra-low insertion loss by using self-packaged multi-layer suspended line is proposed. Two transmission paths with different electric-lengths are used to produce positive phase slope, which would bring a negative group delay, while a coupled line is used for matching, and the commonly applied absorption resistors are not required.The NGD circuit has been fabricated and measured, and the design has been demonstrated with a measured NGD time of À2.84 ns, a NGD bandwidth of 34 MHz, a low insertion loss/signal attenuation (S 21 ) of no more than 2.73 dB, and a S 11 attenuation of about 27.8 dB. Both self-packaging and metallized air cavities are used to reduce the wave leakage, and the multiple via holes usually used for electromagnetic shielding are saved, which greatly reduce the fabrication complexity.

Reconfigurable negative group delay circuit with tunable group delay flatness

“…It can be seen that when C 1 increases and C 2 decreases, the ripple of τ g  f 0 near the center frequency f 0 can be decreased. When the center frequency changes from f 0 to f 1 , the group delay, C 1 , and C 2 could be determined by Equations ( 9) and (10).…”

“…All of these NGDCs in References [1–16] can provide only a fixed negative group delay (NGD) time and cannot satisfy the applications on tunable delay shifter 17 and reconfigurable non‐Foster elements for squint‐free beamforming networks 18 . To obtain the reconfigurable NGDCs, several circuits have been designed 19–27 .…”

“…7 However, the circuits in References [5][6][7] suffer from large signal attenuation. To reduce the loss of the signal, the NGDCs containing amplifiers, 8,9 the selfpackaged multi-layer suspended lines, 10 and the lossy transmission lines [11][12][13][14] were proposed. In References [11][12][13][14], the layout of the circuit is more flexible without lumped elements and can be designed for many different shapes.…”

“…Besides, the lossy NGD circuit with bandpass characteristic has been analyzed 15 and verified by a timedomain experimental test. 16 All of these NGDCs in References [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] can provide only a fixed negative group delay (NGD) time and cannot satisfy the applications on tunable delay shifter 17 and reconfigurable non-Foster elements for squint-free beamforming networks. 18 To obtain the reconfigurable NGDCs, several circuits have been designed.…”

A self‐packaged SCPW negative group delay circuit and its integration with power divider

“…In the past few years, distributed NGD circuits have been developed by using absorptive technique, 17 matching/self‐matching, 18 and signal interference technique, 19 et al, and by these ways, S 11 can be importantly attenuated, which is helpful to overcome the influence of return loss to the source, and effectively eliminate the instability of the microwave system terminal. In the recent years, multi‐band NGD circuit, 20 center frequency and group delay tunable NGD circuit, 21 wideband 22 and low loss 23 NGD circuits, and even bandpass NGD model 24 also have been developed. It is noted that most of the designs need resistors to absorb the reflected waves to get matching.…”