Abstract
A novel circuit theory of all-pass Negative group delay (NGD) function is investigated. The NGD function is implemented with unity direct chain feedback (UDCF) system. The active circuit is built with an operational amplifier in feedback with a lossy transmission line (TL). The UDCF topology S-parameter model is established versus TL parameters. The NGD analysis is elaborated from the frequency dependent transmission coefficient. The NGD behavior characterization is developed. The synthesis method allowing to determine the UDCF topology parameters in function of the targeted NGD values, gain and reflection coefficient is formulated. The all-pass NGD function is validated with a proof-of-concept (POC) design. Frequency and time domain simulations confirm the feasibility of the innovative all-pass NGD function. With S-parameter analysis, it was shown that the UDCF circuit exhibits NGD up to -7-ns with gain more than 0-dB and reflection coefficient -20-dB. More importantly, time-domain analysis illustrates how the transient tested voltage outputs can be in advance compared to the input.
Highlights
Despite the spectacular development of the modern technology, the delay effect remains an open problem in several areas of engineering [1]–[4]
The function is elaborated with the innovative unity direct chain feedback (UDCF) topology consisted of an operational amplifier in feedback with the network of a resistive element associated with a lossy cable
The UDCF topology theory is originally emanated with S-parameter modelling
Summary
Despite the spectacular development of the modern technology, the delay effect remains an open problem in several areas of engineering [1]–[4]. B. Ravelo et al.: All-Pass NGD Function With TL Feedback Topology these delays is still an open challenge for most of electronic design and research engineers. An uncommon delay correction technique based on negative GD (NGD) less familiar to common electronic design and research engineers has been developed, too [18]. This counterintuitive technique is aimed to realize the signal delay cancellation. The NGD function generation in passive circuits is accompanied by signal absorption inducing inherent losses [32], [33] To overcome the latter effect, active circuit topologies based on the use of RF transistors have been developed recently [34]. To simplify the analytical expression, the operational amplifier is assigned with voltage conversion gain as an independent frequency real positive quantity: G(jω) ≈ g
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