Negative Impedance Converter Circuit Research Articles

Analysis, Design and Realization of Negative Impedance Converter Circuit with Current Feedback Operational Amplifier

Analysis, Design and Realization of Negative Impedance Converter Circuit with Current Feedback Operational Amplifier

Physically Oriented Design of Negative Capacitors Based on Linvill’s Floating Impedance Converter

In this article, we present a physically oriented design of broadband RF negative non-Foster capacitors. The design procedure is based on the matrix decomposition of Linvill’s floating negative impedance converter (NIC). The decomposition allows optimization of the NIC circuit regarding the accuracy of generated capacitance. Furthermore, it provides a clear physical picture of the influence of particular circuit elements on the system properties. The methodology is verified by the design and measurements of a negative capacitor in a 0.5–2 GHz range, suitable for applications in bandpass filters with the NIC-based impedance inverters. Experimental results were found to be in good agreement with the theoretical predictions, verifying the correctness of the presented approach.

Nonlinear modeling, time-domain analysis and simulation of non-Foster elements

In this paper, the structure of a common field-effect transistor (FET)-based negative impedance converter (NIC) that behaves as a negative capacitor is presented. The nonlinear modeling, analysis, and simulation of this non-Foster structure are presented in the time domain and the transient response of the circuit can be used to study the stability of the circuit. For the analysis of the circuit performance, the linear time-dependent modeling approach is used. This method is based on determination of the circuit parameters at each step according to parameters of the previous steps, bias voltages, and the input signal. Results of the proposed method for analysis of non-Foster circuit are compared with those of nonlinear analysis using commercial software, which shows a good agreement together and the proposed method is validated. Based on the analysis, the nonlinear capacitance of non-Foster circuit is extracted and based on the simple second order model of current source of FET, the analytic model of negative capacitor is extracted and improved by curve fitting. The proposed model results have a good agreement with simulation results of NIC's circuit.

A Broadband GaN pHEMT Power Amplifier Using Non-Foster Matching

Non-Foster matching is applied to design a multi- octave broadband GaN power amplifier (PA) in this paper. The bandwidth limitation from high-Q interstage matching is overcome through the use of negative capacitor, which is realized with a negative impedance converter (NIC) using the cross-coupled GaN FETs. For high power operation over the entire bandwidth, the natural interstage matching is optimized for the upper subfrequency band and the lower subfrequency band is compensated for by the negative capacitance presented by non-Foster circuit (NFC). Detailed analysis is presented to understand the frequency and power limits of NIC circuits for PA applications. Two negative impedance matched PAs (NMPAs) are fabricated with 0.25- $\mu$ m GaN pHEMT process. The implemented PA with $2{\times}$ combining shows the output powers of 35.7–37.5 dBm with the power added efficiencies of 13–21% from 6 to 18 GHz. The $4{\times}$ combining PA achieves over 5 W output power from 7 to 17 GHz. The NFC boosts the efficiencies and power below 12 GHz to achieve broadband performance without using any lossy matching or negative feedback. To our knowledge, this is the first demonstration of NIC-based broadband amplifiers with multi-watt-level output power.

Low-Power Negative Inductance Integrated Circuits for GHz Applications

A negative impedance converter (NIC) design is proposed to obtain a negative inductance of $L=-1 {\rm nH}$ operating from 0.1 to 6 GHz. The design is based on Linvill's open circuit stable topology, and it is implemented by 65 nm CMOS process to achieve a low power negative inductance integrated circuit. The NIC circuit is attached to a 1.2 V dc power supply and consumes 5 mW of power. The simulation and theoretical results are compared with the measurement, and good agreements are obtained.

Broadband Fast-Wave Propagation in a Non-Foster Circuit Loaded Waveguide

Frequency independent fast-wave (FW) propagation with phase velocity greater than the speed of light can be ideally realized in a dielectric medium whose relative permittivity is positive, but less than 1. Conventionally, FW propagation is implemented by non-TEM waveguides or antiresonance-based metamaterials, which suffers from the narrow bandwidth due to the dispersion. In contrast, non-Foster circuits provide a brand new method for reducing the dispersion so as to broaden the bandwidth. This paper demonstrates broadband FW propagation in a microstrip line that is periodically loaded with non-Foster circuits. Discrete transistor-based non-Foster circuits functioning as negative capacitors are successfully designed with the novel modified negative impedance converter circuits. A -10-pF negative capacitor over a bandwidth of 10-150 MHz has been implemented. The fabricated circuits have been integrated into a microstrip line to form a FW waveguide. The retrieved phase velocity of the effective medium from the measured S-parameters characterizes a stable and causal FW medium with constant phase velocity of 1.2c from 60 to 120 MHz, and this has been further verified by Kramers-Kronig relations and the near-field measurements along the waveguide. In conclusion, a stable, causal, and broadband FW waveguide has been achieved by means of transistor-based non-Foster circuits. The implemented broadband FW propagation can potentially be applied in broadband leaky-wave antennas and cloaking techniques.

UHF Electrically Small Box Cage Loop Antenna With an Embedded Non-Foster Load

Traditional impedance-matching methods typically employ matching networks at the antenna input terminals. Alternatively, the antenna may be embedded with a non-Foster load to enhance the radiation bandwidth. This method is demonstrated here with the design of an electrically small box cage loop antenna (ka ~ 0.37). Simulated results using ideal non-Foster components are compared against a negative impedance converter (NIC) circuit realization. These results show that the VSWR bandwidth is improved 8 × by using the NIC circuit. Simulated radiation efficiencies are also presented for the first time.

Loading artificial magnetic conductor and artificial magnetic conductor absorber with negative impedance convertor elements

AbstractThe general properties of a frequency selective surface loaded with negative impedance converter (NIC)‐based active loads are discussed from a theoretical perspective.The stability problem associated with NIC circuits embedded in artificial magnetic conductor (AMC) and AMC absorber applications is studied using pole‐zero analysis. The requirements and constraints for achieving stable operation with enhanced bandwidth using negative capacitance as realized by a floating NIC network are derived. Furthermore, it is shown that it is nearly impossible to simultaneously implement a negative capacitor and a negative inductor to such structures. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2111–2114, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27019

Vibration control of plates through hybrid configurations of periodic piezoelectric shunts

Periodic arrays of hybrid-shunted piezoelectric actuators are used to suppress vibrations of an aluminum plate over broad frequency bands. Commonly, piezoelectric-shunted networks are used for individual mode control, through tuned, resonant resistive/inductive circuits, and for broadband vibration attenuation, through negative impedance converters. Periodically placed resonant shunts allow for broadband reduction resulting from the attenuation of propagating waves in frequency bands which are defined by the spatial periodicity of the array and by the shunting parameters considered on the circuit. Such attenuation typically occurs at medium–high frequencies, while negative impedance converter networks are effective in reducing the vibration amplitudes of the lower modes of the structure. In this article, the combination of periodic resonant shunts and negative impedance converter networks on the same aluminum panel is studied to verify the possibility of combining the advantages of the two concepts. Both numerical and experimental investigations demonstrate that broadband attenuation is achieved in the mid–high frequency regimes due to the presence of resistive/inductive networks, while the combination with negative impedance converter circuits is responsible for amplitude reduction of the full frequency spectrum. Numerical simulations and frequency response measurements on a plate demonstrate that an attenuation region of about 1000 Hz is achieved with a maximum 8 dB vibration reduction.

Generation and classification of CCII and ICCII based negative impedance converter circuits using NAM expansion

AbstractA new simplified generation method of negative impedance converter circuits (NIC) is introduced. The generation method is based on nodal admittance matrix expansion starting from the input admittance of the NIC circuit terminated by a load rather than treating the NIC as a two‐port network element. The four pathological elements, namely nullator, norator, voltage mirror and current mirror, are used in the generation procedure. Two classes of the NIC pathological circuits are defined; each class includes two types. Eight pathological NIC circuits are generated for each class. Two alternative current conveyor and inverting current conveyor‐based realizations for each pathological circuit based on alternative pairing of the pathological elements are defined resulting in a total of 16 NIC circuit for each class and a total of 32 NIC circuits. A new NIC‐based circuits realizing floating negative impedances are also introduced. Copyright © 2010 John Wiley & Sons, Ltd.

Broadband, Efficient, Electrically Small Metamaterial-Inspired Antennas Facilitated by Active Near-Field Resonant Parasitic Elements

The possibility of using an active internal matching element in several types of metamaterial-inspired, electrically small antennas (ESAs) to overcome their inherent narrow bandwidths is demonstrated. Beginning with the Z antenna, which is frequency tunable through its internal lumped element inductor, a circuit model is developed to determine an internal matching network, i.e., a frequency dependent inductor, which leads to the desired enhanced bandwidth performance. An analytical relation between the resonant frequency and the inductor value is determined via curve fitting of the associated HFSS simulation results. With this inductance-frequency relation defining the inductor values, a broad bandwidth, electrically small Z antenna is established. This internal matching network paradigm is then confirmed by applying it to the electrically small stub and canopy antennas. An electrically small canopy antenna with k? = 0.0467 that has over a 10% bandwidth is finally demonstrated. The potential implementation of the required frequency dependent inductor is also explored with a well-defined active negative impedance converter circuit that reproduces the requisite inductance-frequency relations.

Eddy-Current Displacement Transducer With Extended Linear Range and Automatic Tuning

Design details and measurement results of the eddy-current displacement transducer with extended linear range and automatic tuning are presented. The transducer is based on a resonant impedance inversion method of transfer curve linearization where the displacement probe circuit is kept in resonance by the resonance control loop. The transducer exhibits an extended linear range due to the compensation of displacement probe losses by a negative impedance converter (NIC) at the transducer input. Particular attention is paid to the NIC design and its temperature compensation. The new voltage-controlled NIC circuit is introduced, which can easily be realized with a standard commercial integrated circuit (LM 1496). Details of the transducer's reference generator and the NIC control voltage generator are also presented. The transducer's linear range extends from 0.25 to 3.75 mm (approximately 44% of the 8-mm probe diameter) while maintaining nonlinearity within plusmn2% F.S. This result is, at least, a 75% improvement to the best commercially available eddy-current displacement transducers (a linear range of 80 mil ~2 mm for an 8-mm probe). Further linearization can be achieved by postlinearization of the detected signal.

SINGLE CFA-BASED NICs WITH IMPEDANCE SCALING PROPERTIES

Negative impedance converter circuits (NICs) are important building blocks in design and manufacturing of analog and mixed mode integrated circuits. In this paper, a catalogue of single-current feedback amplifier-based negative impedance converter circuits having impedance scaling properties is proposed. Various examples are presented to illustrate the versatility of the proposed NIC circuits.

Improvement of Sensitivity in Flexural-Type Piezoelectric Sensor Using Negative Impedance Converter Circuit

In this study, an appropriate negative impedance converter (NIC) circuit is designed to improve the receiving sensitivity of a flexural-type piezoelectric sensor. The negative electric elements of the NIC circuit reduce the mechanical resistance of the sensor in resonance, and consequently control the vibration characteristics. Experimental results show that the receiving sensitivity of the designed sensor with the NIC circuit can be improved such that it is much higher than that of a sensor without the circuit.

PSpice Simulation on Piezoelectric Vibrator with Negative Impedance Converter Circuit

To simulate the electromechanical characteristics of a piezoelectric transverse mode vibrator with negative impedance converter (NIC) circuit, we propose a new simulation model for Pspice implementation, which is coupled to the distributed constant equivalent circuit for a piezoelectric vibrator with divided electrodes and the NIC circuit including an active device, such as operational amplifier. The usefulness of the model is demonstrated by comparing the simulation results with experimental ones.

Q-Value Control of Piezoelectric Vibrator Using Operational Amplifier Circuit

In application of a piezoelectric vibrator to some electronic devices such as gyro-sensors and piezoelectric ceramic transducers, it is very useful if the value of the resonance quality factor (Q-value) can be controlled electrically. For achievement of such an ideal, application of a negative impedance converter circuit (NIC circuit) to a piezoelectric vibrator is considered in this work. We applied several negative circuit elements to a piezoelectric vibrator in order to control the Q-value and achieve high performance of it. That is, this work deals with Q-value control of a piezoelectric vibrator by series connection of the NIC circuit, consisting of an operational amplifier, to the vibrator.

The quartz crystal oscillator realization using current conveyors

The analysis, design, and realization of a single pin quartz oscillator based on the current conveyor negative impedance converter (NIC) is presented. NIC circuits have the optimal input static characteristic and good dynamic performances for quartz oscillator design. A short analysis of a single pin crystal oscillator is shown by means of general oscillation theory. The obtained results are applied to a new quartz oscillator circuit design. The proposed oscillator has low crystal Q-factor damping, reliable oscillation build-up, isolated output point, and a wide range of operating frequencies. The circuit is suitable for realization in bipolar integrated technology. The results were experimentally confirmed. >

Negative impedance converter with a translinear implementation

A new negative impedance converter circuit, which is a current inversion type (I-NIC), is described. The basic cell consists of a mixed translinear loop comprising two pnp and two npn bipolar transistors. This cell is used in conjunction with a constant current source and two complementary current mirrors. The characteristics and the properties of the practical realization are presented and discussed. A new bandpass filter, which is a current processing circuit, using the I-NIC and a current-controlled current source (CCCS) are also introduced. Experimental results are given.

Some negative impedance converters

Four new transistor-resistor negative impedance converter circuits are presented, two of the voltage-inversion type and two of the current-inversion type. Their gain-product sensitivities are tabulated.

Negative-Impedance Converters

This paper is devoted to the device properties of the negative-impedance converter (NIC), the derivation of potential NIC circuits and their compensation in order to achieve an exact NIC. The behavior of the NIC as a function of frequency and means of extending its useful frequency range are presented. Attention is also devoted to the sensitivity of the NIC to variations in active and passive parameter values and to means of reducing the sensi- tivity.