Design and Test of Innovative Three-Couplers-Based Bandpass Negative Group Delay Active Circuit

Abstract

An innovative design method of bandpass (BP) negative group delay (NGD) active circuit is developed. The BP NGD topology consists originally of octopole and hexapole coupled line (CL) couplers. The NGD active circuit is validated by a prototype implemented in hybrid technology. The measured results are in good agreement with simulations. The CL-based passive circuit generates BP NGD performance with simulated and measured results showing NGD level of approximately -12 ns having 1.97 GHz center frequency with -11 dB transmission coefficient and -16 dB reflection coefficient. To compensate the loss, active circuit was fabricated by cascading the passive circuit with a microwave amplifier. Subsequently, the previous BP NGD performance is achieved with 0 dB gain. Moreover, a notable active microwave device characterization is performed with the NGD prototype via nonlinear measurements. It was found that the tested NGD prototype operates with 10-dB noise figure, 21 dBm P1dB compression, 29 dBm and 41 dBm OIP3.

Design Theory of Compact Power Divider with Reconfigurable Power Division and Negative Group Delay Characteristics

“…In RF circuits, the NGD phenomenon is observed within a narrow frequency band, it will increase linearity resulting in enhanced performance of a wireless communication system 18 as in the case of squint-free series-fed antenna arrays 19 . A distributed passive band pass NGD circuit cascaded with a microwave amplifier is presented in 20 . All works mentioned earlier, are successful in realizing functions like tunable bandwidth, frequency, power division, or NGD.…”

Reconfigurable negative group delay circuit with tunable group delay flatness

“…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.…”

Design theory of compact power divider with reconfigurable power division and negative group delay characteristics

“…In RF circuits, the negative group delay phenomenon is observed within a narrow frequency band, it will increase linearity resulting in enhanced performance of a wireless communication system 21 as in the case of squint-free series-fed antenna arrays. A distributed passive bandpass negative group delay circuit cascaded with a microwave amplifier is presented in 22 . The mathematical equations for calculating group delays associated with the magnitudes of transmission coefficients at a power division ratio k 2 for designed operating frequency is given in 23 .…”