Phase Shift Network Research Articles

Large Bandwidth Digital Phase Shifters With All-Pass, High-Pass, and Low-Pass Networks

Large bandwidth phase shifters using a combination of an all-pass network (APN), a high-pass network (HPN), and a low-pass networks (LPN) are presented. An exact equiripple phase-shift response is first derived for an infinite series of an APN using phase superposition. However, the realization is impractical and the topology is modified by truncating the series of the APN. A pair of properly designed HPN and LPN is added to compensate for the phase error introduced by the truncation. To verify the topology, phase-shifting networks of 90° and 180° with a bandwidth from less than 100 MHz to more than 2 GHz are designed and measured. A frequency ratio of 35 and 25 has been achieved by the 90° and 180° phase-shifting networks, respectively.

Inkjet-Printed Two-Dimensional Phased-Array Antenna on a Flexible Substrate

In this letter, we present a two-dimensional 2-bit 4 $\,\times\,$ 4 phased-array antenna on a flexible Kapton substrate fabricated using inkjet printing. Printed carbon nanotube thin-film transistors (CNT-TFTs) form the switching elements in the phase-shifting network. A multilayer interconnection scheme has been utilized to fully package the subsystem and enable convenient access of the control lines to the 64 CNT-TFTs. By appropriately controlling the on and off states of the TFT switches using a computer mainframe, beam steering of a 5-GHz RF signal at four steering angles of $\theta = 0^{\circ},$ $\varphi = 0^{\circ};$ $\theta = 14.5^{\circ},$ $\varphi = 0^{\circ};$ $\theta = 20.7^{\circ},$ $\varphi = -45^{\circ}$ ; and $\theta = 34^{\circ},$ $\varphi = -26.5^{\circ}$ are experimentally demonstrated. The insertion loss and the power consumption by the switch array are measured to be 8.17 dB and 11.2 mW, respectively .

Anticipating, complete and lag synchronizations in RC phase-shift network based coupled Chua’s circuits without delay

We construct a new RC phase shift network based Chua’s circuit, which exhibits a period-doubling bifurcation route to chaos. Using coupled versions of such a phase-shift network based Chua’s oscillators, we describe a new method for achieving complete synchronization (CS), approximate lag synchronization (LS), and approximate anticipating synchronization (AS) without delay or parameter mismatch. Employing the Pecora and Carroll approach, chaos synchronization is achieved in coupled chaotic oscillators, where the drive system variables control the response system. As a result, AS or LS or CS is demonstrated without using a variable delay line both experimentally and numerically.

N-way switch based on Rotman lens

A single pole multi-throw RF switch has been developed based on a Rotman lens. The Rotman lens is used in reflection mode wherein a short circuited phase shifter network replaces the array port antennas. An input signal fed to a single beam port can, depending on the phase slope of the phase shifter network, be routed to any of the remaining beam ports. An unoptimised proof-of-concept 8-way switch based on a conventional Rotman lens design is demonstrated at 12 GHz.

Light Weight and Conformal 2-Bit, 1$\,\times\,$4 Phased-Array Antenna With CNT-TFT-Based Phase Shifter on a Flexible Substrate

This paper presents the development and characterization of an ink-jet printed 2-bit, 1×4 phased-array antenna (PAA) system on a flexible Kapton polyimide substrate utilizing carbon nanotube thin-film transistors (CNT-TFTs) as switching elements in the phase-shifting network. A multilayer metal inter connection strategy is used to fabricate a complete PAA system with control lines. By appropriately controlling the ON and OFF states of various switches, a 4.99 GHz signal is steered from 0° to -27°, and the measured far-field radiation patterns agree very well with the simulated data. Bending tests performed on the fabricated system at bending radii of 6.5 cm, 9.5 cm, 12 cm, and 24 cm also demonstrate good agreement with the simulations.

Analog Beamforming in MIMO Communications With Phase Shift Networks and Online Channel Estimation

In multiple-input multiple-output (MIMO) systems, the use of many radio frequency (RF) and analog-to-digital converter (ADC) chains at the receiver is costly. Analog beamformers operating in the RF domain can reduce the number of antenna signals to a feasible number of baseband channels. Subsequently, digital beamforming is used to capture the desired user signal. In this paper, we consider the design of the analog and digital beamforming coefficients, for the case of narrowband signals. We aim to cancel interfering signals in the analog domain, thus minimizing the required ADC resolution. For a given resolution, we will propose the optimal analog beamformer to minimize the mean squared error between the desired user and its receiver estimate. Practical analog beamformers employ only a quantized number of phase shifts. For this case, we propose a design technique to successively approximate the desired overall beamformer by a linear combination of implementable analog beamformers. Finally, an online channel estimation technique is introduced to estimate the required statistics of the wireless channel on which the optimal beamformers are based.

Broadband Five-Port Direct Receiver Based on Low-Pass and High-Pass Phase Shifters

A simple five-port direct receiver achieving broadband performance and high local oscillator to RF isolation is presented. The new circuit comprises three power detectors exhibiting high series impedance, four resistors, and two low-pass and two high-pass phase shifters. It is shown that the phase-shift networks can be designed to optimize receiver operation over a theoretical decade bandwidth. A 300-MHz-2.7-GHz prototype is built and measured to prove feasibility of this proposal.

A 0.18-$\mu\hbox{m}$ CMOS GFSK Analog Front End Using a Bessel-Based Quadrature Discriminator With On-Chip Automatic Tuning

A fully integrated 2-MHz Gaussian frequency-shift keying (GFSK) analog front end for low-IF receivers is presented. The analog GFSK demodulation uses a Bessel-based quadrature discriminator and a differentiator-based data decision circuit, eliminating the need for analog-digital converters while enabling high sensitivity and large frequency offset tolerance. The analog front end consists of a fifth-order Butterworth low-pass prefilter, a seven-stage limiter, a quadrature discriminator with a fourth-order Bessel phase-shift network, a fourth-order Butterworth low-pass postfilter, and a differentiator-based data decision circuit. The prefilter, Bessel phase shifter, postfilter, and differentiator are built using identical <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Gm</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> cells and tuned across process variations with a single master-slave phase-locked loop. The GFSK analog front end is implemented in a 1.8-V 0.18-mum CMOS process, recovering 1-Mb/s input data from a 2-MHz GFSK signal with maximum frequency deviation of plusmn160-kHz, frequency offset tolerance from - 38% to +47%, and input sensitivity of -53 dBm and consuming 7 mA of current.

180$^{\circ}$ and 90$^{\circ}$ Phase Shifting Networks With an Octave Bandwidth and Small Phase Errors

A new phase shifting network for both 180deg and 90deg phase shift with small phase errors over an octave bandwidth is presented. The theoretical bandwidth is 67% for the 180deg phase bit and 86% for the 90deg phase bit when phase errors are plusmn2deg. The proposed topology consists of a bandpass filter (BPF) branch, consisting of a LC resonator and two shunt quarter-wavelength transmission lines (TLs), and a reference TL. A theoretical analysis is provided and scalable parameters are listed for both phase bits. To test the theory, phase shifting networks from 1 GHz to 3 GHz were designed. The measured phase errors of the 180deg and the 90deg phase bit are plusmn3.5deg and plusmn2.5deg over a bandwidth of 73% and 102% while the return losses are better than 18 dB and 12 dB, respectively.

A Novel Circuit Architecture for High Performance of High-order Subharmonic Mixers

A novel circuit architecture for high performance of high-order subharmonic (SH) mixers is proposed in this paper. According to the specified harmonic mixing order, one or more mixer diodes sub-arrays and corresponding power divider as well as phase shift network for RF and LO signals are arranged in the circuit. This proposed SH mixer circuit has improved conversion loss, wide dynamic range and high port isolation for high-order SH mixers. By phase cancellation of idle frequencies, the proposed SH mixer circuit can eliminate complicated design procedure of idle frequency circuits; by phase cancellation of leakage LO power to RF and IF port, and leakage RF power to LO port, the mixer circuit can get high port isolation in LO-IF/RF and RF-LO. The increased antiparallel diode pairs in each sub-array will also lead to well performance by lowering effective series resistance. The proposed SH mixer circuit can be easily realized with power divider and phase shift network for RF and LO signals.

STUDY ON AN UWB PLANAR TAPERED SLOT ANTENNA WITH GRATINGS

A new miniature ultra-wideband exponential tapered slot antenna with gratings, which is fed by a 180 degree microstrip phase shifter network, has been introduced in this paper. The switch characteristic and the reflecting loss of the phase shifter is also analyzed. Some subminiature rectangular gratings are etched at the front and back end, as a result of which, the inner band characteristic is improved and the frequency band of the antenna is extended to more than 3 : 1 (S11 < −10 dB). The radiation pattern has good direction property in the entire bandwidth and favorable symmetrical endfire radiation characteristic as well as more than 10 dB gain in the central frequency band.

A 2-D Phase-Detecting/Heterodyne-Scanning Retrodirective Array

A 2-D retrodirective array based on phase detection and heterodyne scanning is presented. The system integrates two single voltage-controlled oscillator phase-shifting networks that are autonomously controlled via a phase-detecting array and control circuit that eliminates the R4 path loss typical of other retrodirective arrays. Retrodirectivity is reported for angles of 0deg, +15deg, and -15deg at a transmitting frequency of 6.5 GHz.

Surface detection using a phase-shift laser range finder and neural network

This paper deals with a novel approach for achieving real-time surface recognition. The aim of this study is to detect different kinds of surfaces using a phase-shift range finder and a neural network (NN). The NN architecture is a multilayer perceptron with two inputs, three processing neurons in the hidden layer, and one output neuron. The first and the second inputs receive respectively the amplified and filtered photoelectric signal and the range finder output signal. The NN output is compared with threshold voltages in order to classify the tested surfaces. This recognition system has been studied with data from experimental measurements, achieved with four kinds of surfaces (a plastic surface, a glossy paper, a painted wall, and a porous surface), at a remote distance between the range finder and the target varying from 0.5 to 2 m and with a laser beam incidence angle with respect to the target varying between -π5 and π/5.

Design of Active Noise Control System Using Phase Shift Network for a Hydraulic Surface Grinder

In the present research the feedforward method of Active Noise Control (ANC) using Phase Shift Network (PSN) has been proposed for reducing noise generated by a hydraulic Surface Grinder. The PSN was a simple network whose function was to change the phase of the input wave. A passive damping material was used to prepare a duct of 150 mm × 150 mm × 1960 mm for converting multidimensional random noise into a single dimension. The duct was also utilized for housing two speakers employed in the ANC system. The system when installed on the grinder resulted in a total noise reduction of 13.1 dB(A).

Phase Shifter Merging

Phase shifters are used in conjunction with Linear Feedback Shift Registers and Cellular Automata in order to impose sufficient channel separations on the bit sequences produced by their successive cells. The aim is to reduce structural correlations and/or linear dependencies that are problematic for pseudorandom and pseudoexhaustive built-in test pattern generation (TPG). In this paper we present a synthesis approach that merges the logic of the original TPG mechanism with that of the required phase shifter network and yields a new compact structure that can offer lower area overhead and improved frequency of operation than the existing approach.

A 12-GHz SiGe phase shifter with integrated LNA

This paper presents the design and measurement of a 12-GHz active phase shifter with an integrated low-noise amplifier in SiGe. The phase is controlled with a 1-bit (180/spl deg/) digital phase shifter and a 180/spl deg/ continuous analog phase shifter. The 1-bit digital phase shifter is implemented by switching between a -90/spl deg/ low-pass network and a +90/spl deg/ high-pass network. The analog phase shifter is implemented using a lumped-element loaded line technique where both series and shunt elements are adjusted to continuously vary the phase while maintaining a constant port impedance. Design equations for this constant-impedance phase-shift network are derived and presented. The phase shifter achieves 3.7/spl plusmn/0.5 dB of gain, with a noise figure of 4.4 dB at a center frequency of 11.5 GHz. The total chip size including pads is 1920 /spl mu/m /spl times/ 780 /spl mu/m, and the area of the active circuitry without pads is 1680 /spl mu/m /spl times/ 660 /spl mu/m (1.1 mm/sup 2/).

Vector measurements with combined magnetic and electric field sensors

In this article we describe a vector measurement system consisting of a highly sensitive induction magnetometer and a novel electric field sensor. These elements are combined over a broad range of frequencies (10 Hz–10 kHz) using an active phase shift network to provide real-time vector information about the signal.

Fast-response control circuit for resonant inverters

The design procedure for a fast-response control circuit for resonant inverters is presented. The input to the circuit is a signal proportional to the load current, sensed through a Hall-effect sensor or a current transformer. The heart of the circuit is based on a phase-shift and attenuation network, followed by a comparator. In order to obtain reliable operation of the circuit, the design procedure takes into account factors such as the conditioning and slew rate of the differential voltage applied to the comparator. The additional logic used to implement a full control circuit, capable of operating either in open loop or in a resonance-tracking mode, is also described. This logic includes the dead-time generator needed to avoid the simultaneous turn-on of both transistors in the same inverter leg. The circuit was adjusted to provide a slightly inductive response, and tested in a bridge inverter with a maximum operating frequency of 250kHz. Test results show that the circuit provides good performance during start-up, and over a wide frequency range.

Analysis of resolution for an amplitude-steered array

In 1976, Hughes and Thompson introduced the idea of steering the maximum response of a linear array by amplitude weighting the output signals of the elements, thus eliminating the need for time delays or phase-shift networks. Currently that amplitude-steered array concept is being extended to a broadband two-dimensional array that can be used for real-time three-dimensional imaging. In shifting the use of the amplitude-steered array from underwater acoustic communications to imaging, we must consider different issues of the array's performance such as lateral and axial resolution. For the linear amplitude-steered array, we show that both lateral and axial resolution are limited by the length of the array. The dependence of axial resolution on the length of the array is a unique feature of the amplitude-steered array, leading to an interesting tradeoff between lateral and axial resolution. A theoretical basis for the dependence is developed and simulation results are given.

Reactive power measurement using the wavelet transform

This paper provides the theoretical basis for the measurement of reactive and distortion powers from the wavelet transforms. The measurement of reactive power relies on the use of broad-band phase-shift networks to create concurrent in-phase currents and quadrature voltages. The wavelet real power computation resulting from these 90/spl deg/ phase-shift networks yields the reactive power associated with each wavelet frequency level or subband. The distortion power at each wavelet subband is then derived from the real, reactive and apparent powers of the subband, where the apparent power is the product of the v, i element pair's subband rms voltage and current. The advantage of viewing the real and reactive powers. In the wavelet domain is that the domain preserves both the frequency and time relationship of these powers. In addition, the reactive power associated with each wavelet subband is a signed quantity and thus has a direction associated with it. This permits tracking the reactive power flow in each subband through the power system.