Negative Group Delay Phenomenon Analysis Using Finite Unloaded Quality Factor Resonators

Abstract

Abstract-This paper presents a comprehensive method to analyze negative group delay (NGD) phenomenon at microwave frequency. This method is based on a coupling matrix with finite unloaded quality factor resonators. Unlike conventional NGD circuit topologies that use a lumped resistor R along with bandstop resonators, the proposed topology does not require any R for generating NGD and therefore, provides fully distributed circuit realization. The proposed topology has both source to load and inter-resonator coupling structures. Analytical design equations are provided to obtain predefined NGD with matched input/output ports; the proposed structure therefore does not require any extra matching networks. From analytical analysis, it is also found that the NGD bandwidth as well as magnitude flatness can be controlled by inter-resonator couplings. The proposed design theory is proven through fabrications of NGD circuit at a center frequency of 2.14 GHz. The measurement results are in good agreement with simulations and predicted theoretical results.

A Miniaturized Self-Matched Negative Group Delay Microwave Circuit

“…Moreover, the circuit size of the proposed NGD circuit is much smaller than the previous works [14][15][16][17][20][21][22].…”

“…The proposed NGD circuit has the same level of NGD time but provides lower insertion loss than the circuits in [16] and [20]. For the NGD circuits in [17] and [21][22][23], the NGD level is too small. In addition, except [14] and [15], the proposed NGD circuit has better figure of merit (FoM), which is defined as…”

“…To obtain input and output matching without extra circuits, matched NGD circuits have been discussed [19][20][21][22]. In [19], a passive lumped network is based on a bridged tee circuit with a theoretically matched response.…”

“…In order to simultaneously satisfy input-and output-port matching, another λ/4 impedance transformer is required to symmetrically configure two coupled-line sections, which increases the size of circuits. In [21,22], the design of an NGD circuit is based on coupling matrix approach with finite unloaded quality-factor resonators, which are realized by two-end open-circuited λ/2 microstrip lines with the need for lossy substrates. This method increases the design complexity and reduces the use flexibility.…”

A Broadband Switch-Less Bi-Directional Amplifier with Negative-Group-Delay Matching Circuits

“…NGD networks can be classified as passive and active circuits. Passive NGD circuits can be implemented by using RLC resonators [11,12], finite unloaded quality-factor resonators [13], the feedback loop technique [14], or signal interference techniques [15,16]. There is loss generated in the NGD networks.…”