Pole Frequency Research Articles

Design and analysis of MISO bi-quad active filter

ABSTRACTIn this paper, a multiple-input single-output (MISO) voltage-mode bi-quad active filter using voltage differencing voltage transconductance amplifier (VDVTA) is designed and analysed. The filter can realize several functions such as low-pass (LP), high-pass (HP), band-pass (BP), band-reject (BR) and all-pass (AP). The proposed configuration employs three input voltages and generates a single output voltage. The filter characteristics, i.e., pole frequency (ωp) and quality factor (Q) are electronically tunable through the bias current of the VDVTA. The filter performance is analysed through sensitivity analysis in presence of parasitics as well as process, voltage and temperature fluctuations. The proposed design is implemented in a 45-nm CMOS technology and simulated using Virtuoso Analog Design Environment of Cadence.

Simple two operational transconductance amplifiers‐based electronically controllable bilinear two port for fractional‐order synthesis

This Letter introduces a new circuit topology of the simple electronically controllable voltage-mode bilinear two port (BTP) employing two operational transconductance amplifiers. The proposed two-port circuit is completely resistorless and contains only a grounded capacitor. It has a high-impedance input (a simple cascading of sections is possible) and allows an independent electronic adjusting of zero and pole frequency of the transfer function. The operation of the BTP circuit is demonstrated for two different locations of the pole and zero frequency coordinates. Moreover, a direct application of four BTPs in fractional-order integrators (order -0.11 and -0.33) with phase shifts -10° and -30° is shown. Design specification is verified by experimental measurements.

Overlapping Laser Micro-Doppler Feature Extraction and Separation of Weak Vibration Targets

The laser-detected micro-Doppler (MD) effect is more likely to achieve precision target identification and recognition because of its high-accuracy estimation ability. MD features overlapping in the time–frequency (TF) are encountered in targets with similar micromotion parameters, which cannot be solved with one-channel detection. In this letter, a novel separation method based on a constrained particle filter (PF) in a time-varying autoregressive (TVAR) model is developed to solve this extremely underdetermined problem. First, the TVAR model for a multicomponent MD signal is established, and the connection between the interested instantaneous frequency (IF) and model poles is analyzed. Then, the continuity characteristic of the IF law is used to design a constraint condition for a PF assuming that the laser MD effect obeys the sinusoidal frequency modulation form. By fusing the constraint into the process of particle update and weight computation, the IF curve for each component is correctly separated through the well-tracked pole trajectories. Finally, the performances of the presented method and traditional method are compared for a TF overlapping scenario. The simulation results verify the validity and necessity of the new method; meanwhile, the low-level computational complexity makes it possible for real-time processing.

Electronically Tunable First-Order Filters and Dual-Mode Multiphase Oscillator

This paper introduces two novel circuits of first-order universal filter that comprise single multiple outputs dual-X current conveyor transconductance amplifier and one grounded capacitor only. The first circuit is of current-mode type, and second is of transadmittance-mode type. Both the circuits are suitable to modern IC technology and offer the feature of ease of cascadability. The proposed circuits do not need any passive component matching constraints. Moreover, the pole frequency of both the circuits is electronically tunable. The transadmittance-mode type circuit also provides an interesting feature of electronic and independent tuning of amplitudes of output currents without affecting the pole frequency. To check the applicability of the proposed circuit, a dual-mode multiphase oscillator is also derived from the proposed transadmittance-mode type filter. It provides two quadrature voltage outputs and four quadrature current outputs simultaneously. The oscillation frequency and condition of oscillation are orthogonally and electronically controllable. The non-ideal and parasitic analyses of all the proposed circuits are investigated, and HSPICE simulation results are depicted to confirm the proposed theory. Furthermore, transadmittance-mode type first-order universal filter is experimentally verified using commercially available ICs.

Bandpass filters using multi‐mode square ring resonators

A novel scheme of a multi-mode square ring resonator (MMSRR) is proposed in this study. To analyse the characteristics of the proposed resonator, the odd- and even-mode based method is used, which shows that the basic type of resonator has five resonant modes and three transmission zeros (TZs). The frequencies of the transmission poles and TZs can be changed by varying the sizes of the transmission lines of the resonator flexibly. By varying properly the parameters of the resonator, a dual-band bandpass filter (BPF) is designed with central frequencies of 1.78 and 3.04 GHz, respectively. To explore further the performance of the proposed MMSRR, two single-band BPFs with controllable bandwidth are designed. The bandwidth of the filter can be tuned in the range of 138.6 MHz by changing only the characteristic impedance of middle microstrips, which is much higher than previous works. Furthermore, to improve the band-to-band isolation of dual-band filters, a stub is imposed in the middle of the proposed resonator, which can improve significantly the band-to-band isolation. Simulation and measurement results show that the isolation is >26.3 dB. The results of the simulation and measurement are in good agreement.

Improved nonlinear dynamic inversion control for a flexible air-breathing hypersonic vehicle

This paper presents an improved nonlinear dynamic inversion control approach for the longitudinal dynamics of a flexible air-breathing hypersonic vehicle. The control design of the approach is based on a control-oriented model that represents the nominal state. By establishing a three inputs and three outputs control system, the control-oriented model in this study has full vector relative degree, without dynamic extension. To maintain tracking performance in the presence of disturbances, a nonlinear disturbance observer is adopted to estimate the disturbances. To achieve good transient performance, an adaptive damping term is proposed to the pitch dynamics. Based on approximate input–output linearization, linear control theory is applied to design a pole placement controller for the equivalent linear system. The damping ratio, natural frequency, and simple pole of the pole placement controller are optimized by the genetic algorithm along with the full nonlinear model of the vehicle. During the optimization, 11 uncertain parameters are introduced to the nonlinear model. Monte Carlo evaluation shows that the optimized pole placement controller provides robust tracking of reference trajectories. Simulation results indicate the effectiveness of the proposed control approach.

Design and implementation of quadrature bandpass sigma-delta modulator used in low-IF RF receiver * * Project supported by the National Natural Science Foundation of China (Nos. 61471245, U1201256), the Guangdong Province Foundation (No. 2014B090901031), and the Shenzhen Foundation (Nos. JCYJ20160308095019383, JSGG20150529160945187).

This paper presents the design and implementation of quadrature bandpass sigma-delta modulator. A pole movement method for transforming real sigma-delta modulator to a quadrature one is proposed by detailed study of the relationship of noise-shaping center frequency and integrator pole position in sigma-delta modulator. The proposed modulator uses sampling capacitor sharing switched capacitor integrator, and achieves a very small feedback coefficient by a series capacitor network, and those two techniques can dramatically reduce capacitor area. Quantizer output-dependent dummy capacitor load for reference voltage buffer can compensate signal-dependent noise that is caused by load variation. This paper designs a quadrature bandpass Sigma-Delta modulator for 2.4 GHz low IF receivers that achieve 69 dB SNDR at 1 MHz BW and -1 MHz IF with 48 MHz clock. The chip is fabricated with SMIC 0.18 μm CMOS technology, it achieves a total power current of 2.1 mA, and the chip area is 0.48 mm2.

Novel First Order Current Mode MOS-C Phase Shifters

In this work, novel first order MOS-C phase shifter structures are proposed in NMOS and PMOS configurations. Core circuits consist of only three transistors and a single capacitor. The pole frequency of the phase shifters can be easily controlled by the bias voltage. The presented circuits in this work bring advantages such as low power consumption and small chip area when compared to other works including large numbers of active and passive elements in the literature. Furthermore, the proposed circuits are designed with a simple design automation flow that is proper for MOS-Only or MOS-C architectures. It is shown by simulations that the simulation results agree with the theoretical results for a wide frequency range. DOI: http://dx.doi.org/10.5755/j01.eie.24.1.20157

Design and Analysis of Tunable Voltage Differencing Inverting Buffered Amplifier (VDIBA) with Enhanced Performance and Its Application in Filters

This paper proposes a high performance tunable Voltage Differencing Inverting Buffered Amplifier (VDIBA) where transconductance of VDIBA is enhanced by using programmable positive feedback technique and bandwidth is enhanced by using resistive compensation technique. The enhanced performance of proposed VDIBA is demonstrated by presenting detailed frequency analysis. Furthermore, it is verified that transconductance of proposed VDIBA can be enhanced up to 10.6 mS at tuning current (Ic) of 100 µA. Moreover, resistive compensation technique enhance bandwidth of propose circuit up to 263 MHz. To illustrate the effectiveness of proposed circuit, voltage mode universal biquad filter is designed as an application example. The pole frequency of proposed filter is tunable in range of 10.5---83.4 MHz. The proposed VDIBA and its filter applications are designed and simulated using TSMC 0.18 µm CMOS technology in Cadence virtuoso schematic composer at ± 0.6 V supply voltage.

Fractional-order low-pass filter with electronic tunability of its order and pole frequency

Abstract This paper presents novel solution of a fractional-order low-pass filter (FLPF). The proposed filter operates in the current mode and it is designed using third-order inverse follow-the-leader feedback topology and operational transconductance amplifiers (OTAs), adjustable current amplifiers (ACAs), auxiliary multiple-output current follower (MO-CF) as simple active elements. The filter offers the beneficial ability of the electronic control of its order and also the pole frequency thanks to electronically controlled internal parameters of OTAs and ACAs. As an example, five particular values of fractional order of the FLPF were chosen and parameters of the filter were calculated. Similarly, also electronic control of the pole frequency of the filter was studied. The design correctness and proper function of the filter are supported by simulations with CMOS models and also by experimental laboratory measurements. Comparison of the simulation results of the proposed filter for two different approximations of the parameter s α is also included.

Синтез системы управления безмостовым корректором коэффициента мощности в режиме прерывистого тока

The classical systems for control of power factor correctors (PFC) are subordinated-type control systems with two feedback loops: a slow loop serving to stabilize the output voltage and a fast loop serving to shape a sinusoidal input current. Designing of these control systems involves difficulties due to the need of ensuring stable operation of the external and internal loops in the specified range of input voltage and output power. The power factor correction converters with linear input volt-ampere and adjustment characteristics do not require the current loop because the input current will repeat the network voltage waveform due to the power circuit features. The specific features of synthesizing a single-loop control system for a power factor corrector that uses a bridgeless single-phase PFC as the power circuit. Such a structure operating in the choke discontinuous conduction mode has the property of self-correcting the power factor and can operate at a network voltage either higher or lower than the input voltage. The use of a boost and buck-boost PFC makes it possible to do without a secondary DC-DC converter serving to match the boost PFC with the load. The adjustment characteristics of a bridgeless PFC operating in discontinuous and continuous conduction modes are presented. The converter nonlinear model linearized using the Matlab/Simulink tools and a manually linearized model in the form of a control transfer function are constructed. It is shown that with the bridgeless PFC operating in the intermittent current mode, the frequencies of right-half plane zeroes and high- frequency poles are located much higher than the frequency of the voltage loop unity gain and do not affect the stability of converter operation. The switched model involving a correction loop synthesized in the Matlab/Simulink environment was investigated, and it has been demonstrated that the converter shows stable operation in the entire range of input voltage and output power. Hence, it can be stated that the used continuous and single-loop control system can be used for inverting, series-parallel, flyback, and other converters operating in the intermittent current mode and having the power factor self-correction ability.

Speed Control of a Single Phase Induction Motor Using Step-down Cycloconverter

Induction motor is a constant speed machine when operated from the mains. However it is necessary to vary the speed of the motor in some applications. The speed of a motor basically depends on the supply frequency and number of poles. While the frequency can easily be changed without changing the entire structure of the motor, the same cannot be said for the number of poles. This paper examines the use of cycloconverters to vary the speed of single phase induction motors. Cycloconverters work on changing the supply frequency to vary the speed of the motor. With the aid of three push buttons connected to the microcontroller and the program written on it, the speed of the motor was varied in three steps, at F, F/2 & F/3. The microcontroller sends the gating pulse through an optocoupler to trigger the thyristors in a dual bridge providing the alternating signal needed to drive the motor. As the frequency decreases, the speed of the motor also decreases. The cycloconverter was used on a single phase induction motor and the result shows that it can vary the speed of an induction motor.

A High-Selective Frequency Selective Surface With Hybrid Unit Cells

In this paper, a novel frequency selective surface (FSS) is proposed. It has two metal layers and the configurations of the unit cells of these two layers are different, so-called hybrid unit cells. The designed FSS has three transmission zeros and steep roll-offs at the edges of the passband. In our design process, the top layer is used to achieve two transmission zeros at the edges of passband and the bottom layer is used to achieve wideband performance and transmission zero at the right side of the passband. The effects of the geometrical parameters on the frequencies of transmission poles and zeros are analyzed. By establishing an equivalent circuit, the matching impedance network is obtained quickly by Microwave Office and the flatness and insertion loss of the passband are improved after introducing the matching impedance network. The prototype of the proposed FSS is manufactured and tested. The measured −1.5-dB passband is from 13.2 to 19 GHz, and its relative bandwidth can achieve 36%. The measured results verify the design. This FSS is a good candidate to strengthen the performances of $Ku$ -band satellite and $Ku$ -band active radar.

MOSFET-Only filter design automation based on polynomial regression with exemplary circuits

In this work, a novel design automation method is presented for easy construction of MOSFET-Only or MOSFET-C filters. In contrast to previous works in the literature, the proposed algorithm is simple since it uses polynomial fitting models obtained from SPICE data in order to reformulate small signal parameters and some DC characteristics of MOSFET’s. Polynomial regressive models facilitate to interact between design constraints (power, area, speed, pole frequency etc.) and design variables (operating voltages, currents and device dimensions). In this regard, two novel agile MOSFET-Only filters produced with the proposed automation process are presented in order to qualify the automation flow. The produced filters are simulated in LT-SPICE and CADENCE-SPECTRE environment by using 0.18 µm TSMC technology. These agile filters can easily be used in a wide range of applications such as encrypted communications or very high frequency circuits. In addition, it is shown that there is a good agreement between proposed design automation flow and simulations.

Retrospective Cost Adaptive Control: Pole Placement, Frequency Response, and Connections with LQG Control

Avast range of technological systems-from aerospace vehicles to chemical processes to Segways-depend on feedback control. These applications typically rely on a combination of classical and modern control techniques, logic for mode switching, and diagnostics for fault detection to ensure safety and reliability, all of which are validated and verified through simulation and testing. A feedback control system is the quintessential cyberphysical system, in which real-time digital computing elements interact bidirectionally with the full complexity of the real world through noisy transducers and limited communication channels [1]. In many applications, the control system is crucial to safe operation, and the potential benefits of new ideas and techniques for feedback control must be weighed against the risk of unanticipated response and/or failure.

Anisotropic dyonic black brane and its effects on holographic conductivity

We investigate a massive gravity theory involving the SL(2, R) symmetry and anisotropy. Due to the SL(2, R) invariance of the equations of motion, the complex con-ductivity of this model transforms covariantly under the SL(2, R) transformation and the ratio of DC conductivities in different spatial directions is preserved even after the SL(2, R) transformation. We further investigate AC and Hall conductivities by utilizing the Kubo formula. There exists a Drude-like peak in the region with a small anisotropy, while such a Drude peak disappears when anisotropy becomes large. We also show that the complex conductivity can have a cyclotron frequency pole even beyond the hydrodynamic limit.

Synthesis and Analysis of Electronically Adjustable Fractional-Order Low-Pass Filter

A proposal of a fractional ([Formula: see text])-order low-pass filter is presented in this paper. The proposed filter operates in the current-mode and it is designed using Multi-Output Current Followers (MO-CFs), Dual-Output Current Follower (DO-CF), Dual-Output Adjustable Current Amplifier (DO-ACA) and Adjustable Current Amplifiers (ACAs) as active elements within the presented topology of the filter. The filter possesses ability to electronically control its order and also the pole frequency by changing the current gain of current amplifiers (ACAs) already present in the structure. Three different values of the order and pole frequency of the proposed low-pass filter were tested as an example. Design of the proposed filter is supported by simulation and experimental results. Simulations of the circuit are carried out in PSPICE simulator with behavioral models of used active elements. The experimental laboratory measurements are performed with the help of available devices forming equivalent circuits. Simulations and experimental results of the electronical control of the order and pole frequency are compared in this contribution.

Resistorless Current-Mode First-Order All-Pass Filter with Electronic Tuning Employing Low-Voltage CBTA and Grounded Capacitor

In this paper, a new realization of a current-mode first-order all-pass filter (APF) using a single active building block (ABB) and one grounded capacitor is presented. As the ABB, the current backward transconductance amplifier (CBTA) is used, which is one of the most recently reported active elements in the literature. The theoretical results are in detail verified by numerous SPICE simulations using a new low-voltage implementation of CBTA. In the design, the PTM 90[Formula: see text]nm level-7 CMOS process BSIM3v3 parameters with [Formula: see text]0.45[Formula: see text]V supply voltages were used. The proposed resistorless CBTA-C APF provides easy electronic tuning of the pole frequency in the frequency range from 763[Formula: see text]kHz to 17.6[Formula: see text]MHz, which is more than one decade. Maximum power dissipation of the circuit is 828[Formula: see text][Formula: see text]W at bias current 233[Formula: see text][Formula: see text]A. Nonideal, parasitic effects, sensitivity analyses, temperature and noise variation, current swing capability, and Monte Carlo analysis results are also provided. Compared to prior state-of-the-art works, the proposed CBTA-C APF has achieved the highest figure of Merit value, which proves its superior performance.

MISO current mode bi-quadratic filter employing high performance inverting second generation current conveyor circuit

This paper presents static and dynamic studies of a new CMOS realization for the inverting second generation current conveyor circuit (ICCII). The proposed design offers enhanced functionalities compared to ICCII circuits previously presented in the literature. It is characterized by a rail to rail dynamic range with high accuracy, a low parasitic resistor at terminal X (1.6Ω) and low power consumption (0.31mW) with wide current mode (3.32GHz) and voltage mode (3.9GHz) bandwidths.Furthermore, a new MISO current mode bi-quadratic filter based on using ICCII circuits asactive elements is proposed. This filter can realize all standard filter responses without changing the circuit topology. It is characterized by active and passive sensitivities less than unity and an adjustment independently between pole frequency and quality factor. The operating frequency limit of this filter is about 0.8GHz with 0.674mW power consumption.The proposed current conveyor circuits and bi-quadratic filter are tested by TSPICE using CMOS 0.18µm TSMC technology with ±0.8V supply voltage to verify the theoretical results.

Realization of current-mode biquadratic filter employing multiple output OTAs and MO-CCII

This paper presents a low voltage low power operational transconductance amplifier circuit. By using a source degeneration technique, the proposed realization powered at ±0.9V shows a high DC gain of 63dB with a unity gain frequency at 3.5MHz, a wide dynamic range and a total harmonic distortion of −60dB at 1MHz for an input of 1Vpp. According to the connection of negative current terminal to positive voltage terminal of double output OTA circuit, a second generation current conveyor (CCII-) has been realized. This circuit offers a good linearity over the dynamic range, an excellent accuracy and wide current mode of 56MHz and voltage mode of 16.78MHz cut-off frequency f-3dB.Thereafter, new SIMO current-mode biquadratic filter composed by OTA and CCII as active elements and two grounded capacitors is implemented. This filter is characterized by (i) independent adjusting of pole frequency and quality factor, (ii) it can realize all simulations results without changing the circuit topology, (iii) it shows low power consumption about 0.24mW. All simulations are performed by Cadence (Cadence Design Systems) technology Tower Jazz 0.18μm TS18SL.