A 4–1 Multiplexer-Based Frequency Discriminator Used for Oscillator Phase Noise Suppression

2.45 GHz Band Quadrature Microwave Frequency Discriminators with Integrated Correlators Based on Power Dividers and Rat-Race Hybrids

“…Consequently, it can be concluded that the quality of the microwave frequency discriminator with the modified correlator is not worse than that with the developed The constant coefficients used in Equations ( 13) and (14) were found in the calibration processes of the microwave frequency discriminators with the correlators that were developed. In these cases, it was assumed that the input frequency-measured frequency transfer characteristics of the microwave frequency discriminators would be approximated by the single straight lines.…”

“…Microwave frequency discriminators (MFD) and microwave phase discriminators (MPhD) are the fundamental elements of instantaneous frequency measurement (IFM) systems [1][2][3][4][5][6][7][8][9][10]. Moreover, MFDs and MPhDs are attractive for phase noise measurements of microwave oscillators [11][12][13][14][15][16]. They can also work as simple demodulators in microwave FM receivers [17,18] and in monopulse direction finding systems of microwave emitters [19] and can be used for frequency identification [20].…”

“…The measurement of the phase difference is performed by the microwave phase discriminator, which is fed by the PPhSFN. The main segment of MPhD is a microwave multiport (six-port, for instance), which consists of microwave splitters and combiners [7][8][9]14,18,19,26]. There are also known quite simply as so-called single-function microwave frequency discriminators (SFMFD).…”

“…These types of instruments, i.e., SFMFD, can be used in cases when the accuracy of a frequency measurement is not a main requirement, 2 of 16 but their small size plays a particularly significant role. High measurement resolution and accuracy are the parameters that characterize the so-called quadrature microwave frequency discriminators (QMFD) [1][2][3][4][5][7][8][9][10]14]. The QMFDs may contain, depending on the implementation, several microwave splitters and at least two vector summation devices or mixers.…”

Polarization-path-frequency entanglement using interferometry and frequency shifters

“…Microstrip-based discriminators have been seen to achieve high sensitivity and high dynamic range, with a recent work being able to attain a frequency resolution of 16 MHz by using open-loop spiral resonators instead of the more conventionally used coupled resonators [60]. High resolution and accuracy have also been obtained with quadrature microwave frequency discriminators [61][62][63][64][65][66]. Adaptive spectrum sensing techniques based on group delay induced by Brillouin scattering in optical fiber has been shown to be able to temporally discriminate two-tone signals with a resolution of 60 MHz [67].…”