Transmission Line Phase Research Articles

Analysis and design of an efficient, fully integrated 1–8 GHz traveling wave power amplifier in 180 nm CMOS

Traveling wave amplifiers (TWAs) offer the advantage of broadband amplification and a closed set of equations that allow deriving the RF gain by means of treating TWAs as discrete transmission line approximations. Up to now, however, the significant losses associated with CMOS integrated inductors have been neglected. This work presents a new approach for determining the transmission line losses and phase constants that will bring about an enhanced gain prediction accuracy. The theory is verified by means of a realized design example. The working principle of the integrated DC supply inductor is discussed, whose performance is based on the inductors self-resonance effect. When applying a supply voltage Vdd of 2.4 V, the measured compression point P1 dB and the power added efficiency PAE at 2.4 GHz amount to 16.9 dBm and 19.6%, respectively. At 5.5 GHz, a value of 16.6 dBm for P1 dB and an associated PAE of 13.9% are achieved. The peak RF gain for these output power values reaches 11 dB, and values greater than 8 dB are obtained up to 7 GHz.

A novel structure for dc bias on varactors in composite right/left-handed transmission lines phase shifter using Ba0.25Sr0.75TiO3 thin film

Tunable ferroelectric varactors, consisting of two series connected capacitors using Ba0.25Sr0.75TiO3 thin film, have been applied in composite right/left-handed (CRLH) transmission lines (TLs) phase shifters. The CRLH circuit, with a length of 3330 µm, is a coplanar design integrated on a high resistive Si substrate. A novel circuit of dc bias pads is designed to provide direct connection and therefore ensure the same applied dc voltage across each varactor. Both simulation and experimental results demonstrated the unique features of CRLH TLs, showing a differential phase shift with flat frequency dependence characteristics. Under 10 V dc voltages, the phase shift is 35° and the differential phase shift is flat between 6.8 and 8.8 GHz. The figure of merit is 4.1° dB−1 around 7.5 GHz.

RFID Coverage Extension Using Microstrip-Patch Antenna Array [Wireless Corner

In this paper, a UHF-band 2 times 2 microstrip phased-array antenna is designed and implemented to extend the coverage of an RFID reader system. The phased-array antenna has four microstrip-patch antennas, three Wilkinson power dividers, and a transmission-line phase shifter. These are printed on a dielectric substrate with a dielectric constant of 4.5. The array has dimensions of 34 cm times 45 cm, operating at a frequency of 867 MHz, as specified in RFID Gen2 protocol European standards. The phased-array antenna has a measured directivity of 12.1 dB, and the main-beam direction can be steered to angles of plusmn 40deg, with a HPBW of 90deg. The phased-array antenna is used as the receiving antenna in a commercial reader system. Experimental results indicate that the coverage of the RFID system with the phased-array antenna is superior to the coverage with a conventional broader-beamwidth microstrip-patch antenna. The proposed system can also be used for a wireless positioning system.

Duality and Superposition in Split-Ring-Resonator-Loaded Planar Transmission Lines

Three types of coplanar transmission lines loaded with split-ring resonators (SRRs) and including series gaps and/or shunt wires are analyzed in this letter. The phase advance originally predicted for these microstructures can be modified and their frequency selectivity can be enhanced while maintaining the advantage of miniaturization. Full-wave electromagnetic simulations and measurement of different prototypes operating in S- and C-frequency bands are performed for retrieving the effective permittivity and permeability. It is shown that right-handed transmission bands can be obtained slightly below the resonance frequency of the SRRs, giving an effective control of the propagation characteristics in magnitude and phase of these planar transmission lines.

A LOW VOLTAGE TUNABLE ANALOG PHASE SHIFTER UTILIZING FERROELECTRIC VARACTORS

ABSTRACT A distributed transmission line phase shifter was implemented by periodically loading a coplanar transmission line using ferroelectric varactors in a shunt configuration. A single dc bias applied to the phase shifter circuit provides a large relative phase shift. A relative phase shift of ∼ 305 degrees was obtained at 20 GHz for a dc bias of only 5 V.

Passive varactor tuned equivalent transmission line phase shifter at C-band in 0.25 µm BiCMOS

The design of a C-band phase shifter fabricated in a commercial 0.25 µm BiCMOS technology is presented. Phase shift is enabled by tuning the varactors of a lumped element, equivalent of a transmission line. Only one single control voltage is required. The circuit is optimised for adaptive antenna combining on the basis of the 802.11a standard and matched for 50 Ω terminations. Within a frequency band ranging from 5.2 to 5.8 GHz, the circuit yields a phase control range of higher than 195°, an insertion loss of only 3.6±1.5 dB, return losses higher than 12 dB and a 1 dB compression point above 10 dBm. The chip and circuit areas amount to 0.6 and 0.25 mm2, respectively. To the knowledge of the authors, at comparable phase control range, the lowest insertion loss for a passive phase shifter integrated in silicon reported to date is demonstrated.

Distributed transmission line phase shifter using MEMS switches and inductors

Distributed MEMS transmission line (DMTL) phase shifter has been developed using planar inductors. The design consists of a coplanar waveguide line capacitively and inductively loaded by the periodic set of electrostatic force actuated microelectromechanical system switches as capacitors and inductors. By applying a single bias voltage on the line, the characteristic impedance can be changed, which in turn changes the phase velocity of the line and creates a true time delay phase shift. The governing equations for the impedance and loss are derived. The ABCD matrix is defined for a unit and multi-cell DMTL phase shifter to extract scattering parameters equations. The device containing 15 cells calculated, simulated, and fabricated. Fabricated results show that the device can be considered as a new type of the DMTL phase shifter with small size, higher phase shift and acceptable scattering parameters.

Phase-Encoding for On-Chip Signalling

A novel self-timed communication protocol is based on the phase-modulation of a reference signal. The reference signal is sent on a number of transmission lines and the data can be recovered observing the sequence of events on the these lines. Employing several lines increases the number of states hence reducing the number of symbols required for a transmission. A new encoding algorithm is described which generates symbol-dependent matrices which are used to control the phase of transmission lines. The protocol concept, the algorithm and analysis of the system, together with simulation results, are presented.

Fast Computation and Stable Convergence Technique for Unbalanced Load Flow Calculation in the Large Scale System

This paper presents a new method of unbalanced load flow calculation to improve complexity by the method of advanced symmetrical coordinates. Usually, the electric power system has been calculated only by positive phase sequence component on the assumption that three phase transmission lines and loads are balanced. However, many ultra high voltage transmission lines are not transposed, therefore mutual inductances cause negative sequence current in trunk transmission system. Negative sequence current causes the heating of the generators and transformers. Therefore, the three phase sequence component should be calculated accurately.We examined fast computation and good convergence performance of unbalanced load flow calculation by the models of three phase transmission lines, transformers and loads. The proposed method is not the phase coordinate system but the method of symmetrical coordinates. This technique decreases numerical complexity by the use of simplified jacobian matrix. The convergence performance of this method is inferior to usual Newton-Raphson method. In consequence, the problem of poor convergence performance is improved by the technique for newly developed deceleration Newton method.

A DSP based frequency domain approach for classification of transmission line faults

This paper employs a digital signal processing (DSP) based frequency domain approach using wavelet multi-resolution analysis (MRA) to overcome difficulties such as fault inception angle, fault impedance and fault distance associated with conventional time domain approach employing voltage and current based measurements for fault classification in case of digital relaying of transmission line. The frequency domain approach for fault classification algorithm uses wavelet MRA technique to extract the features of the current signals based on harmonics generated at the instant of occurrence of fault due to abrupt change of currents in a three phase transmission line. Since choice of particular wavelet plays a vital role for extracting features of generated harmonics, therefore an attempt has been made in this proposed research to extensively investigate using 16 wavelets to establish the superiority of Db4 wavelet over other standard wavelets for accurate fault classification.

Printed and Integrated CMOS Positive/Negative Refractive-Index Phase Shifters Using Tunable Active Inductors

This paper presents a printed and an integrated bi-directional tunable positive/negative refractive-index phase shifter utilizing CMOS tunable active inductors (TAIs). The printed phase shifter is comprised of a microstrip transmission line (TL), loaded with series varactors and a shunt monolithic microwave integrated circuit (MMIC) synthesizing the TAI. Using the TAI extends the phase tuning range and results in a low return loss across the entire tuning range. The integrated circuit (IC) phase shifter replaces the TLs with suitable lumped L-C sections. This enables integrating the entire phase shifter on a single MMIC, resulting in a compact implementation. The TAI used for both phase shifters is based on a modified gyrator-C architecture, employing a variable resistance to independently control the inductance and quality factor. The TAI is fabricated in the 0.13-mum CMOS process and operates from a 1.5-V supply. The TAI chip is used to implement the TL phase shifter, which achieves a phase of -40deg to +34deg at 2.5 GHz with less than -19-dB return loss from a single stage occupying 10.8 mm times 10.4 mm. The IC phase shifter is fabricated in the same process and achieves a phase from -35deg to +59deg at 2.6 GHz with less than -19-dB return loss from a single stage occupying 550 mum times 1300 mum.

Analysis of Current Unbalance In Transmission Systems With Short Lines

The analysis of current unbalance in power systems with short transmission lines is presented. Measurements in the Israel Electric Transmission System as well as numerical simulations of three-phase load flow have revealed lines with a high level of current unbalance. It is found that significant current unbalance on short transmission lines may take place due to the following reasons: inherent asymmetry of untransposed transmission lines;) presence of line traps used for power-line carriers (PLC); electromagnetic coupling between lines on double-circuit towers; superposition of current symmetrical components in lines under light loading. It is shown that the current asymmetry may lead to overcurrents in individual phases of transmission lines as well as to growth of the magnetic field in proximity of the lines

Study of equivalent circuits for open-ring and split-ring resonators in coplanar waveguide technology

A study of open-ring resonators and split-ring resonators is performed in terms of equivalent circuits. The resonant particles can be intrinsically described by simple LC circuits; even if their resonant behaviours are caused by conceptually different phenomena, either distributed or quasi-static resonances can be attributed for designs with similar geometrical dimensions. When inserted on the back-plane of a coplanar waveguide, and combined with short-circuiting wires on the top-plane, the periodic structures designed so far exhibit a certain pass-band where backward waves are generated. The left-handed behaviour is proved through the analysis of the phase of different length transmission lines and can be observed for both types of resonators. Full-wave simulations and experimental results performed on manufactured prototypes validate the overall good performance of the proposed equivalent circuits. Detailed models for the different elements of the unit-cells are provided on the basis of different analytical approaches.

A 0.13-$\mu$m CMOS Phase Shifter Using Tunable Positive/Negative Refractive Index Transmission Lines

This letter presents a tunable positive/negative refractive index transmission line (TL) phase shifter utilizing active circuits. It comprises a microstrip TL loaded with series varactors and a shunt monolithic microwave integrated circuit (MMIC) to synthesize a tunable inductor. This implementation increases the phase tuning range and maintains the input and output matching of the phase shifter across the entire phase tuning range, while eliminating the need for bulky passive inductors. The phase shifter is capable of providing both positive and negative phase shifts. The MMIC tunable inductors are fabricated in a 0.13-mum CMOS process and operate from a 1.5-V supply. The phase shifter achieves a phase of -40deg to +34deg at 2.5GHz from a single stage with less than -19dB return loss, and better than 1.1-dB insertion loss at 2.5 GHz. The phase shifter has a 1-GHz bandwidth over which the return loss remains better than 12.1dB

Circuit model and design of silicon‐integrated CRLH‐TLS analogically controlled by MEMS

AbstractWe present an integrated composite right/left handed transmission line (CRLH‐TL) phase shifter analogically controlled by means of a MEMS series capacitor. The device is based on coplanar waveguide (CPW) technology and operates at a central frequency of 18 GHz. An accurate and physical circuit model including parasitics inherent to this MEMS realization is presented. We describe the method used to design the presented structure, which consists in a mixed approach using the developed circuit model and full‐wave simulations. The MEMS‐controlled CRLH‐TL has been fabricated and characterized, showing good agreement with predicted performances. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2496–2499, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22014

Composite right/left handed transmission line phase shifter using ferroelectric varactors

A composite right/left handed (CRLH) transmission line (TL) phase shifter, using ferroelectric (Ba/sub 0.25/Sr/sub 0.75/TiO/sub 3/) varactors as tunable element, is presented for the first time. It is theoretically and experimentally demonstrated how the unique features of CRLH TLs, enables a differential phase shift with flat frequency dependence around the center frequency. The experimental prototype is a coplanar design integrated on a high resistive Si substrate. It includes four CRLH T-unit cells and has a physical length of 3850/spl mu/m. The ferroelectric varactors are realized in parallel plate version. Under 15-V dc bias applied over each varactor, the differential phase shift is flat around 17GHz and has an absolute value of 50/spl deg/.

24 GHz RF-MEMS Phase Shifter with Non-Galvanic Electromagnetic Coupling Fabricated in Silicon-Bulk Technology

This contribution presents a Distributed MEMS Transmission Line (DMTL) phase shifter designed for 24 GHz and fabricated in Silicon-Bulk Micromechanic Technology. Using this technology enables to commonly suspend all capacitive loads on one movable plate and allows full range analog and homogeneous gap adjustment. The first available prototypes of the phase shifter are characterized to provide 5.4 °/mm differential phase shift at 24 GHz and to show 0.1 dB/mm insertion loss. An asymmetric coplanar signal coupler with a center frequency of 24 GHz and 10% bandwidth is used to contact the signal through the substrate of the phase shifter chip and back to a supporting printed circuit board. The normalized measured insertion loss of the coupling structure after simulated optimization is 0.13 dB - 0.17 dB.

Distributed MEMS analog phase shifter with enhanced tuning

The design, fabrication, and measurement of a tunable microwave phase shifter is described. The phase shifter combines two techniques: a distributed capacitance transmission line phase shifter, and a large tuning range radio frequency (RF) microelectromechanical system (MEMS) capacitor. The resulting device is a large bandwidth, continuously tunable, low-loss phase shifter, with state-of-the-art performance. Measurements indicate analog tuning of 170deg phase shift per dB loss is possible at 40 GHz, with a 538deg phase shift per centimeter. The structure is realized with high-Q MEMS varactors, capable of tuning C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> /C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> = 3.4. To our knowledge, this presents the lowest loss analog millimeter wave phase shifter performance to date

Direct-coupled microwave filters with single and dual stopbands

This paper presents new ideas for the design and implementation of microwave filters with single and dual stopbands. They can be realized with waveguide, coaxial, dielectric resonators, or in a planar technology. The new methods represent an advance over present methods in that the resonators are direct coupled, thus avoiding the need for transmission line phase lengths between resonator stubs that tend to degrade performance due to their dispersion and are difficult to adjust during tuning. Three bandstop (BS) configurations are presented. The first will accommodate even or odd characteristics and also asymmetric responses, although some negative or diagonal cross-couplings will be needed. The second resembles the cul-de-sac configuration for bandpass filters and needs no diagonal or negative couplings even for asymmetric characteristics. The third is an application of the cul-de-sac synthesis technique to dual-band bandstop (DBBS) filters. All these BS designs are very similar to regular bandpass filters in their design and realization. The design of a DBBS filter is presented and compared with an equivalent bandpass filter to demonstrate its advantages. Finally, the simulated and measured results of a fourth-degree BS filter design in the novel cul-de-sac configuration are presented.

Fault Analysis of Six Phase Power System Using Six Phase Symmetrical Components

The use of six–phase for power transmission was investigated and tested as an alternative to three phase transmission. High phase order (HPO) transmission systems are those designed to transmit more than three phases of electrical power, normally six phases. A few studies had encountered the fault analysis of the six–phase system with the six symmetrical voltage and currents. In this article, the method of symmetrical components is used to analyze the 23 significant fault types that can occur on the six–phase transmission line with the six symmetrical voltage and current components encountered.