A novel real-time Fourier and inverse Fourier transforming system based on non-uniform coupled-line phaser

A Compact Active Phaser with Enhanced Group Delay Linearity for Analog Signal Processing

“…Among the possible applications of the phaser, there is the frequency discriminator, also referred to as Real-Time Fourier Transformer as presented, for example, in [3]. The principle of such a device is to separate frequency components from a stationary signal by measuring the delay for each of the components.…”

“…Most of the ASP applications require a linear group delay characteristic. Many implementations of phasers have been published in [2][3][4][5][6][7][8]. Among these implementations, only a few have been implemented using a monolithic integrated circuit approach.…”

Design of integrated all‐pass filters with linear group delay for analog signal processing applications

“…It seems that Laso et al 16 were the first to report the realization of a chirped microstrip where the energy spectral density of the input signal was given by the average output power reflected from the device. Other researchers used this type of device to implement real-time Fourier and inverse Fourier transformation 17 and to demonstrate the time magnification (or time stretching) of ultra-wideband (UWB) signals. 15 Recently, transmission line (TL) structures implemented on conventional microwave technologies have been studied and developed for ASP applications, like the realization of a compressive receiver through a composite right-/left-handed (CRLH) TL implemented on a Rogers Duroid 5870 substrate, 9 and a real-time Fourier transformer designed using engineered C-section all-pass networks.…”

“…It seems that Laso et al were the first to report the realization of a chirped microstrip where the energy spectral density of the input signal was given by the average output power reflected from the device. Other researchers used this type of device to implement real‐time Fourier and inverse Fourier transformation and to demonstrate the time magnification (or time stretching) of ultra‐wideband (UWB) signals …”