20. Phase Shifter

We present the design, fabrication and testing of a low-temperature superconducting (LTS) analog microwave variable attenuator. The two-port circuit includes two <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$90^{\circ }$</tex-math></inline-formula> hybrid couplers and a phase shifter to realize a variable attenuation at the output port. The wideband analog phase shifter is implemented using LTS microstrip transmission line (TL) coupled to an array of radio frequency superconducting quantum interference devices (rf-SQUIDs). The phase shift is achieved by passing a dc current through a TL adjacent to the SQUID-loaded microstrip line which controls the flux through the rf-SQUIDs. The proposed variable attenuator shows more than 30 dB of precise analog flat attenuation tuning range over 8 GHz to 12 GHz with a dc control current ranging from 0 mA to 4.5 mA. The device exhibits a wideband operation with variable attenuation seen not only in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X-</i> band but also in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ku-</i> band. The device is fabricated using a multilayer niobium-based superconducting process SFQ5ee by MIT Lincoln Laboratory, and has a compact footprint of 1.3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathrm{mm}^{2}$</tex-math></inline-formula> . To the best of our knowledge, this is the first implementation of a variable attenuator using distributed rf-SQUIDs. This device has implications in a variety of applications such as cryogenic receivers and qubit circuit measurements.

Design and analysis of polarization independent MMI based power splitter for PICs

A novel T-shaped high-power waveguide phase shifter is investigated in this paper. The phase shifter consists of straight waveguides, four 90° H-bend waveguides, a stretching metal plate, and a metal spacer linked with the stretching metal plate. The entire structure for the phase shifter is symmetrical along both sides of the metal spacer. The phase-shifting principle for the phase shifter is to change the microwave transmission path by moving the stretching metal plate and then realize the linear phase adjustment. An optimal design approach of the phase shifter based on the boundary element method is described in detail. On this basis, a T-shaped waveguide phase shifter prototype with a center frequency of 9.3GHz is designed. Simulation results show that the phase shifters can achieve 0°-360° linear phase adjustment by altering the distance of the stretched metal plate to 24mm, and the efficiency of power transmission is more than 99.6%. In the meanwhile, experiments were conducted and the test results are in good agreement with simulation results. The return loss is more than 29 dB, and the insertion loss is less than 0.3 dB at 9.3GHz in the entire phase-shifting range.

In this paper, we verified an arbitrary waveform generator based on a nonlinear transmission line (NLTL). The fabricated arbitrary waveform generator consists of a NLTL harmonic generator, 10dB coupled line couplers, Wilkinson power dividers, band pass filters, low noise amplifiers (LNA), variable attenuators, and NLTL phase shifters. By controlling the bias voltage of attenuators and phase shifters, it is possible to generate a desired arbitrary waveform such as a triangle waveform and a sawtooth waveform in a microwave frequency range.

A novel nonlinear circuit called a "Phase Shifter" is introduced which accurately measures the phase margin of a linear system operating in a feedback control loop. The measurement is made by inserting the phase shifter in the control loop, causing it to undergo self-sustained oscillations (limit cycle) of relatively low amplitude. It is shown that sustained oscillations occur at the gain crossover frequency, and the phase margin is equal to the phase lag of the inserted circuit. A complete analysis of the amplitude and frequency of oscillation, which employs the classical sinusoidal-input describing function, is also given and the stability of the limit cycle and its neighborhood, using the theory of integral manifolds, is included.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Recent advances in the development of Barium Strontium Titanate ferroelectric composition has made possible reasonable performance of ferroeletric phase shifters to frequencies up to 10 GHz. These material improvements, coupled with phase shifter circuit design changes have resulted in phase shifts greater than 360 degrees with less than 6 dB insertion loss. In particular additives to the BaxSr1-xTiO3 composition have been shown to exhibit a consistent electrical phase shift verses DC potential over parameters of temperature and humidity. These ferroelectric material improvements and circuit design changes, included with the development of multiple ferroelectric phase shifters makes possible the fabrication of a low cost electronic scanning antenna. A single four element phase shifter was used with a one dimensional linear antenna array which was constructed on three layers and used an aperture coupled distribution technique. Individual elements of this multiple four element phase shifter were evaluated with respect to uniformity phase shift and insertion loss. The four element antenna was fed by four ferroelectric phase shifters and the phase shifters are corporately fed by the microwave source. The ferroelectric phase shifters are controlled via a dedicated microcontroller which calibrates out element phase variations and provides a real time scan capability for the antenna assembly.

This thesis presents an electronic oscillator circuit operating at C-band which achieves a frequency of 4.5 GHz, a phase noise of -115.75 dBc/Hz at 1 MHz offset from the carrier, a figure of merit of -173.6 dBc/Hz and 21.9 mW of dissipated power. The oscillator is a voltage-controllable injection-locked cross-coupled oscillator which achieves a C-band frequency without the need for integrated-circuit implementation. This was done by using a novel mirror-plane design approach for the design of the selected oscillator topology on printed circuit board technology to minimize parasitics by creating effective chiral twins of prepackaged transistors \& achieve C-band operation. The oscillator provided a method of demonstrating a frequency-tunable single-loop optoelectronic oscillator frequency synthesizer which does not require bandpass filters, phase shifters, power combiners, or power splitters. The 4.5 GHz synthesizer achieved a phase noise of -90 dBc/Hz at a 10 kHz carrier offset using a 200 m optical fiber.

A number of electronic devices such as phase shifters, polarizers, modulators, and power splitters are based on tunable materials. These materials often do not meet all the requirements namely low losses, fast response time, and technological compatibility. Novel nanomaterials, such as single-walled carbon nanotubes, are therefore widely studied to fill this technological gap. Here we show how the dielectric constant of single-walled carbon nanotube layers can be substantially modified by illuminating them due to unique light–matter interactions. We relate the optical excitation of the nanotube layers to the illumination wavelength and intensity, by resistance and capacitance measurements. The dielectric constant is modified under laser illumination due to the change of material polarization and free carrier generation, and is shown to not be temperature-related. The findings indicate that SWCNT layers are a prospective tunable optoelectronic material for both high and low frequency applications.

A rectangular flat printed dipole antenna with a small volume and area. It has the advantages of easy manufacturing and low cost when printing circuits. It can be separated from oscillators, amplifiers, variable attenuators, modulators, and filters. Phase shifter and other modules. Because this antenna does not require a lot of space, it is easy to install in the package structure cover. This antenna has practical value for teaching and can be used as a good subject for learning. It can include Bluetooth, ISM, and 5G has the opportunity to be used in future small products that can be connected to 5G antennas.

Self-interference suppression improvement by employing circular polarized antennas

This study presents a self-correction method for a non-retrodirective cross-eye jamming (NRCJ) system based on the measurement of reference amplitude ratio and phase difference (ARPD). Cross-eye jamming performance is highly sensitive to gain and phase mismatches between the system's dual transmission paths, which can degrade the jamming effectiveness during operation. To address this issue, a reference system (RS) is introduced to measure the transmitted jamming signal in the jamming direction and compensate for deviations by adjusting the NRCJ system's variable attenuator and phase shifter. The RS stores reference ARPD values during initial calibration and compares them with current measurements to update control parameters when errors exceed predefined thresholds. A prototype NRCJ system operating at 8GHz was fabricated, and gain and phase errors of 2 dB and 3° were intentionally induced. Experimental results demonstrate that the proposed method successfully compensates for ARPD errors, reducing the gain and phase deviations to within 0.3 dB and 1°, respectively. Consequently, the magnitude of the cross-eye gain improved from 8.57 to 49.5, and the radar angle tracking error increased from 2.45° to 14.18°. These results confirm that the proposed self-correction approach enhances the robustness and jamming effectiveness of NRCJ systems in practical applications.

This b paper describes theoretical study, modeling and simulation of tunable coupled line phase shifter. This structure is based on basic Schiffman model in which a coupled dispersive microstrip transmission line was used combined with uniform transmission line. The main idea of this work is to design a mixed structure of tunable phase shifter loaded by Varactor diode. A differential phase between two paths of transmission signal was created and tuned using variable capacitance, this phase keeps approximately the same value on the operating frequency band between 0.8 and 1.4GHz. We have evaluated the performances and good variation of phase shifting was denoted with good insertion loss, less than 1.0dB and return losses for both of two signal paths.

Multiple-input-multiple-output is a promising technology to enable spatial multiplexing and improve throughput in wireless communication systems. The phase shifter needed in each element of the phased array to perform the electronic steering of the beam typically introduces a non-ideal transfer function in the signal path and consumes significant area and power, making it a major source of cost and dissipation. To address those issues, this chapter describes a novel technique referred to as localized LO phase-shifting, where the array of phase shifters in the receiver and in the transmitter is replaced by an array of synchronized PLLs, providing the local oscillation to each path, with fine and inherently linear phase regulation. This approach not only helps reduce power consumption and area occupation, in modern CMOS nodes, but also improves phase noise since the beam is formed by the combination of uncorrelated noise sources. To demonstrate the concept, a dual-element LO phase-shifting system, based on fractional-N digital PLLs in the 8.5-to-10.0-GHz range, is implemented in a standard 28-nm CMOS process. Each element occupies 0.23 mm2 of area and dissipates 20 mW of power. An arbitrary phase shift between the LO outputs can be set over the full 360 $$^{\circ }$$ ∘ range with a resolution of 0.7 millidegrees. The measured rms phase accuracy is 0.76 $$^{\circ }$$ ∘ , and the peak-to-peak phase error is 2.1 $$^{\circ }$$ ∘ , without requiring any linearity or gain calibration. Combining the outputs of the two elements, the measured integrated random jitter scales down from 58.5 to 44.6 fs rms.

Nowadays in Indonesia, 3D Radar has been developed to perform a vertical scanning that has multi-functional benefits in telecommunication industry and defence. As a common practice, 3D radar system is frequently used to measure the distance of an object like the aircraft. Therefore, the most important element in radar systems is the phase shifter that has a main role in steering the beam and replacing the rotator function. This final research will focus on the operation of simple Phase Shifter with concerning a 2,9 GHz – 3,1 GHz radar frequency. Phase shifter designed at 3 GHz as the centre frequency within a value return loss ≤ -15 dB, insertion ≥ -4 dB, coupling ≥ -4 dB, isolation ≤ -15 dB, phase difference 45°, 90°, 135°, phase error ≤ 15°, and realized by converting into Microstrip Quadrature Hybrid Coupler 90°. These particular phase shifter uses the type of substrate Rogers R04035B with dielectric constant values (εr) at 3,48, and the thickness of the substrate ( h ) of 1,524 mm. Simulations are performed using Computer System Technology ( CST ) software suite 2015 and assigned the average results each port to return loss value -37,290519 dB, insertion -3,154242 dB, coupling -3,164594 dB, isolation -32,714140 dB, with phase difference 45,00816°, 89,09566°, 90,76276°, 134,85057° and phase error 0,00816°, 0,90434°, 0,76276°, 0,14943°, It is then subsequently realized and measured by Netwotk Analyzer and return loss -30,078370 dB, insertion -3,229792 dB, coupling -3,146129 dB, isolation -42,651590 dB, phase difference 45,15190°, 86,38080°, 93,38538°, 134,36260° and phase error 0,15190°, 3,61920°, 3,38538°, 0,63740°.

A variable attenuator is a critical component at microwave and terahertz frequencies to adjust the signal path loss-gain settings in the system. This facilitates designers and engineers to determine the optimum performance of their measurement systems and instruments. Attenuators, both fixed and tunable, are readily available at microwave frequencies however at submillimeter-wave and terahertz frequencies, design and fabrication are very challenging because such components need to be integrated with compact metal waveguide packaged sub-systems and instruments. In this work, we demonstrate a novel waveguide based variable attenuator at WR1.5 band (500-750 GHz) using a metal coated silicon slab. A piezo electric motor is used to control the position of the slab on the path of the incoming electromagnetic signal to achieve variable attenuation. The amount of attenuation is determined by the volume of silicon slab inside the waveguide and the absorption coefficient of the metal coating.