A Dual-Purpose Reconfigurable Negative Group Delay Circuit Based on Distributed Amplifiers

Abstract

A dual-purpose reconfigurable negative group delay circuit based on distributed amplifiers Abstract-In this letter, a novel reconfigurable negative group delay distributed amplifier (NGD-DA) circuit is proposed. This NGD-DA offers a new method to realize negative group delay. By properly choosing the gain coefficient of each tap for the DA, we can synthesize the negative group delay at the reverse port of the DA in the frequency band of interest, while maintaining a flat gain at the forward port; this results in a dual-purpose DA. Moreover, the proposed NGD-DA is reconfigurable; the phase response at the reverse port can be simply controlled by adjusting the tap gain coefficients, and therefore the bandwidth as well as the amount of negative group delay can be manipulated. The proposed active NGD circuit is validated through theoretical explanation and experimental results.Index Terms-Dispersion engineering, distributed amplifier (DA), dynamic power supply, negative group delay (NGD), superluminal group velocity, transversal filter.

Maximally Flat Negative Group-Delay Circuit: A Microwave Transversal Filter Approach

“…14 illustrates the diagram of an -stage DA in which is the gain coefficient of the th tap amplifier, and indicate the time delay of the th section of the gate line and drain line, respectively. Furthermore, if we choose that , then the transfer functions of the forward and reverse port with respect to the input can be expressed as [12] (26a) (26b)…”

“…Very recently, a novel active NGD circuit using distributed amplifiers (DAs) has been proposed [12]. The active NGD circuit is essentially based on the concept of transversal filters [13], [14], which have been typically used in equalization and pulse shaping.…”

“…However, the desired coefficients in previous work were obtained by the convex optimization, a numerical optimization approach, which usually does not give us exact solutions [12], [15]. Therefore, in this paper, we provide a comprehensive method to analytically derive the desired coefficients for transversal-filter-based NGD circuits, which give exact solutions to realize NGD with maximally flat characteristics.…”

A Miniaturized Self-Matched Negative Group Delay Microwave Circuit

“…This method increases the design complexity and reduces the use flexibility. In addition, some NGD circuits implemented through microwave transversal filter approach can also obtain port matching [23,24], whereas this method demands multi-section structures which increases the circuit size.…”

An active dispersive delay line in GaN MMIC technology for X-band applications

“…In addition, not completely passive configuration, using active devices, are proposed in [10], but operating on narrow bands and at low frequency. The use of a distributed amplifier (DA) is particularly useful to obtain dispersive characteristic [11]. In this contribution a new design methodology is presented for dispersive delay lines which exploits active elements in GaN MMIC technology, to perform the convolution function on broadband at high frequency ranges up to X-band.…”