Synthesis of frequency-independent phase shifters using negative group delay active circuit

Abstract

This article describes a synthesis method dedicated to the design of frequency-independent phase shifters (PSs). This innovative PS structure consists in a transmission line cascaded with a negative group delay (NGD) active circuit so that the absolute constant group delays generated by both of them are identical but of opposite signs. So, in principle, it exhibits a constant overall phase and a group delay close to zero. Broadband linear positive phase slopes are obtained through use of an NGD active circuit whose characteristics are recalled prior to the extraction of the PS synthesis relations. The design and simulations of a PS of compact size are reported. The experimental results confirm the expected frequency-independent transmission-phase value of 145 6 10 with an insertion gain of 2 6 2 dB over a 160% relative frequency band. At last, future prospects allowed by the specific properties of this PS are presented.

Neutralization of LC- and RC-Disturbances with Left-Handed and NGD Effects

“…So, one proposes to exploit the configuration presented by the block diagram depicted in [50]. In the ideal case, the frequency responses as the magnitude, phase and group delay of the correction system must be respectively expressed as:…”

“…The time delay limitation of NGD circuits is investigated in [45][46]. Based on the NGD function, different applications for the design of innovative oscillator [47], balun [48], phase shifters [49][50][51], pulse compression generator [52] and feed forward amplifier [53][54] were developed in electronic areas. In addition, further applications for the reduction of signal delays were also proposed based on the neutralization of the disturbing effects in the electronic systems [51] [55][56][57].…”

Demonstration of negative signal delay with short-duration transient pulse

“…In addition, microwave application for the design of independent-frequency phase shifter is also introduced in [44][45].…”

Synthesis ofn-way active topology for wide-band RF/microwave applications

“…It is based on the topology of the negative group delay (NGD) active cell proposed in Ravelo, Perennec, Le Roy, and Boucher (2007b). Additionally, the functioning of this balun depends on the use of NGD phase shifters independently operating with the frequency (Ravelo, Le Roy, and Perennec 2008;Ravelo, Perennec, and Le Roy 2011) associated with a passive power-splitter. Hence, due to the contributions of reactive element responses, the flatness of the balun transmission gain is generally degraded for the wide band applications.…”