Showing papers on "Negative resistance published in 2003"

Voltage controlled oscillator

Abstract: An LC circuit section and a negative resistance section are provided for an LC-VCO. A pair of output terminals are provided for the LC circuit section and an inductor is connected between the output terminals, and two variable capacitors are connected in series to each other parallelly with the inductor. Further, the LC circuit section is provided with a pair of capacitors and a pair of switches that are connected between the capacitors and a ground potential and consist of NMOS transistors. Moreover, a switch that consists of the NMOS transistor is connected between a node, which is between one capacitor and one switch, and a node, which is between the other capacitor and the other switch, and the two nodes are connected to each other when the switch is closed.

Effects of hot-carrier stress on the performance of the LC-tank CMOS oscillators

Abstract: The effects of hot carrier stress on a fully integrated negative resistance LC-tank CMOS oscillator are investigated. The major effect is the decrease of the amplitude of the oscillation due to degradation in the I-V characteristics of the MOSFETs. The oscillator phase noise increases with stress duration since the amplitude of the oscillation decreases. A change in the biasing of the circuit due to the stress affects the parasitic capacitances in the circuit which in turn cause a slight change in the oscillation frequency.

Analysis and design of negative impedance LC oscillators using bipolar transistors

Abstract: This paper provides an analysis on how the application of emitter degeneration increases the oscillation frequency while improving the output phase noise and tuning range of LC oscillators designed using bipolar transistors Design methodology, simulation results and circuit examples for LC oscillators employing this technique are given

Theoretical investigation of the origin of negative differential resistance in substituted phenylene ethynylene oligomers

Abstract: In the very active area of molecular electronics, individual molecules or self-assembled molecules have been shown to behave as microscopic switches in transistor and diode architectures. In particular, it has been demonstrated that molecular wires inserted into nanopores and positioned between two metallic electrodes can be used as active elements for the fabrication of resonant tunnelling diodes (RTDs), whose I/V characteristics reveal a negative differential resistance (NDR) behaviour (i.e. a negative slope in the I/V curve). In this paper, we describe at the quantum chemical level a possible mechanism, based on conformational effects, rationalizing the experimental observation of an NDR signal in phenylene ethynylene oligomers. We will demonstrate that the origin of the peak profile in the I/V curves can be described on a qualitative basis from the evolution of the one-electron structure of the wires upon application of a static electric field aligned along the molecular axis, which simulates the driving voltage applied between the two electrodes in the RTD devices.

A circuit for high frequency crystal oscillators

Abstract: This paper describes a circuit for high frequency crystal oscillators using an AT-cut resonator in the UHF frequency range. This circuit can be built based on a conventional Colpitts oscillator circuit with a feedback capacitor between the collector terminal and the emitter terminal of a transistor. The new circuit has the characteristic features of low drive level and high negative resistance, while maintaining the equivalent input capacitance of the circuit. Analyzing the equivalent input impedance of the circuit clarifies the effects of the proposed circuit compared with the conventional Colpitts oscillator circuit. The performance of the circuit is verified by an experimental evaluation of a voltage controlled crystal oscillator (VCXO) with a 622 MHz high frequency fundamental (HFF) crystal resonator. This VCXO offers a frequency deviation of /spl plusmn/160 ppm or greater versus a control voltage change of 1.65 V/spl plusmn/1.65 V, a temperature frequency stability of /spl plusmn/30 ppm or less over the range from -40/spl deg/C to 85/spl deg/C, and a frequency stability of /spl plusmn/5 ppm or less versus a supply voltage change of 3.3 V/spl plusmn/03 V. A phase noise level of greater than -100 dBc/Hz at 1 kHz carrier offset frequency is demonstrated.

New realizations of CMOS current controlled conveyors with variable current gain and negative input resistance

Abstract: In this paper two new second-generation current controlled current-conveyors (CCCIIs)-based circuits are proposed. The proposed circuits are variable gain CCCII and CCCII with negative resistance. The design of these circuits is based on a simple CMOS CCCII that has high bandwidth with -3 dB cutoff frequency of 580 MHz. With no signal mirroring used in these configurations, lower harmonic distortion can be achieved. HSPICE simulation results for the proposed circuits are included.

A novel defected ground structure and its application to a microwave oscillator

Abstract: This paper presents a new defected ground structure (DGS) and its application to a microwave oscillator. The presented oscillator is designed so as to use the suggested defected ground structure as a feedback loop inducing a negative resistance as well as a frequency-selective circuit. Applying the feedback loop between the drain and the gate of a FET device produces a high gain and precise phase conversion in the feedback loop. The equivalent circuit parameters of the DGS are extracted by using a three-dimensional EM calculations and simple circuit analysis method. The implemented 9 GHz oscillator provides +8.5 dBm output with high power efficiency over 40%.

X-band AlGaN/GaN HEMT MMIC Vo ltage-Controlled Oscillator

Abstract: Am onolithic AlGaN/GaN HEMT voltage-controlled oscillator has been designed, fabricated and characterized. The oscillator design utilizes a common-gate negative resistance topol- ogy with a multi-finger interdigitated Schottky diode varactor resonator for frequency control. The VCO operating a t1 5 V drain bias and -4 V gate bias, exhibits frequency range between 8.5 and 9.5 GHz with maximum output power of 31.8 dBm across a5 0 ohm load. Maximum power variation does not exceed ± 0.8 dB in the oscillation frequency band. Average phase noise in the bandwith is estimated to be equal to -77 dBc/Hz at 100 kHz offset and -101 dBc/Hz at 1 MHz offset. Average tuning sensitivity is measured to be 120 MHz/V. Oscillator's pulling figure is equal to 139 MHz for 12 dB return loss. Pushing figure is 114 MHz/V. Output power can be increased up to 35 dBm (2.1 W/mm) by setting drain bias voltage at 30 V.

Variable gain voltage/current converting circuit, and filter circuit using the same

Abstract: PROBLEM TO BE SOLVED: To provide a variable gain voltage/current conversion circuit, namely, a gm amplifier which can greatly change a gain range without using a large number of elements. SOLUTION: A parallel circuit of a positive resistor R1 (R2) and a transistor Q3 (Q4) which function as negative resistance is connected in series to transistors Q1 and Q2 for converting voltage/current. A variable voltage source VV is connected between Q3 (Q4) and ground, and a voltage value is controlled to control the resistance value of Q3 (Q4). When the voltage of the variable voltage source VV is changed, the resistance value of Q3 (Q4) changes. Thus, the voltage between the gates/sources of the transistors Q1 and Q2 changes and its gm value also changes. COPYRIGHT: (C)2004,JPO&NCIPI

Method of overtone selection and level control in an integrated circuit CMOS negative resistance oscillator to achieve low jitter

Abstract: A stable high-frequency clock pulse apparatus and method including frequency source, overtone crystal unit coupled with a negative resistance oscillator, a bandpass overtone filter and a drive level control is provided. The apparatus can include a frequency multiplier. The frequency source can be a micromechanical resonator.

Analysis and design of negative resistance oscillators using surface transverse wave-based single port resonators

Abstract: This practically oriented paper presents the fundamentals for analysis, optimization, and design of negative resistance oscillators (NRO) stabilized with surface transverse wave (STW)-based single-port resonators (SPR). Data on a variety of high-Q, low-loss SPR devices in the 900- to 2000-MHz range, suitable for NRO applications, are presented, and a simple method for SPR parameter extraction through Pi-circuit measurements is outlined. Negative resistance analysis, based on S-parameter data of the active device, is performed on a tuned-base, grounded collector transistor NRO, known for its good stability and tuning at microwave frequencies. By adding a SPR in the emitter network, the static transducer capacitance is absorbed by the circuit and is used to generate negative resistance only over the narrow bandwidth of the acoustic device, eliminating the risk of spurious oscillations. The analysis allows exact prediction of the oscillation frequency, tuning range, loaded Q, and excess gain. Simulation and experimental data on a 915-MHz fixed-frequency NRO and a wide tuning range, voltage-controlled STW oscillator, built and tested experimentally, are presented. Practical design aspects including the choice of transistor, negative feedback circuits, load coupling, and operation at the highest phase slope for minimum phase noise are discussed.

A CMOS neural oscillator using negative resistance

Abstract: A CMOS neural oscillator using negative resistance has been designed and fabricated in an AMI 0.5 /spl mu/m double poly technology through MOSIS. The proposed neural oscillator consists of a nonlinear resistor with negative resistance as well as standard OTAs and capacitors. Simulations of a network of oscillators demonstrate cooperative computation. Measurements of the fabricated oscillator chip confirm the input-gated oscillatory behavior of the cell.

Two-port element high frequency oscillator using slot line

Abstract: PROBLEM TO BE SOLVED: To provide a highly productive high frequency oscillator which facilitates a variety of circuit designs including the impedance matching and readily provides an increased oscillation output power SOLUTION: The high frequency oscillator has a substrate, a resonator circuit which is disposed on one principal surface of the substrate and consists of a closed loop-shaped slot line including an inner conductor and an outer conductor, an electric boundary point set on the slot line, a two-port negative resistance element for connecting between the inner conductor and outer conductor, and an output line electrically connected to the slot line COPYRIGHT: (C)2003,JPO

Simulation of a novel bipolar-fet type-s, negative resistance circuit

Abstract: A new circuit which uses FET and bipolar transistor is given. It exhibits Type-S differential negative resistance and a theoretical explanation is appended along with PSPICE simulation.

X band BiCMOS SiGe 0.35 /spl mu/m voltage controlled oscillator in parallel and reflection topology and external phase noise improvement solution

Abstract: This paper reports the design of two X band voltage controlled oscillators (VCO) implemented in the same ST Microelectronics SiGe BiCMOS technology and using the same active device. One VCO design is based on a parallel topology while the other one is based on a serial topology. The chips work with a single supply voltage of 3.3 V, and the measured phase noise performance for the feedback VCO is -85 dBc/Hz @ 100 kHz offset with a tuning range of 0.5 GHz and the simulated phase noise for the negative resistance VCO is -92 dBc/Hz @ 100 kHz offset with a tuning range of 1.1 GHz. Finally, an off chip solution is proposed to improve the phase noise performance.

Analysis of carbon nanotube intramolecular p-n tunnel junction transistors

Abstract: A theory of intramolecular p-n junction transistors that is based on mesoscopic material parameters is presented. The tunneling rate across each junction was calculated using, the Matsubara-Green's function technique. Characteristics of the transistor such as gain, output voltage versus current, and output voltage versus input voltage were calculated. The results of the theory are compared with experimental data. Our formalism also predicts new features such as voltage steps in the negative differential region of the current-voltage characteristics, and a device with current limiting features.

Lc quadrature oscillator having coupling circuits

Abstract: A quadrature oscillator capable of lowering phase noise and power dissipation is disclosed. The oscillator circuit includes two symmetrical oscillators ( 11 ) ( 12 ) formed by cross-coupled transistor pairs with positive feedback structure to produce negative resistance, two LC circuits ( 13 ) ( 14 ) coupled to the above oscillators ( 11 ) ( 12 ) to produce positive resistance offsetting the negative resistance through the oscillators ( 11 ) ( 12 ), and two coupling circuits ( 15 ) ( 16 ) coupled to the oscillators ( 11 ) ( 12 ) to produce quadrature phase outputs, wherein, the transistor pairs in each coupling circuit ( 15 ) are respectively connected to the corresponding transistor pairs in the two oscillators ( 11 ) ( 12 ), to prevent the operating point of the oscillator transistors from shifting toward the linear region.

Injection-locked push-pull oscillator at 72 GHz band using cross-coupled HEMTs

Abstract: An injection-locked push-pull oscillator at V-band is developed for high purity millimeter wave signal source. Cross-coupled HEMTs are applied for the negative resistance generation across wide frequency range and virtually grounded short-ended lines are used for the resonant circuit instead of lumped inductors. Thanks to the differential operation of cross-coupled HEMTs, the push-pull oscillator was easily implemented by combining the 2nd harmonics of oscillation signal at the drain terminals. Injection signal at the fundamental oscillation frequency is applied at the gate of the current source FET of cross-coupled FETs for stabilizing the oscillation, which performs the amplification and harmonic generation. The designed oscillator was fabricated using 0.15/spl mu/m GaAs pHEMT process. The measurement showed the free-running oscillation around 35.8 GHz and maximum lock range of 1.48 GHz (2.1%) around 71.6 GHz with the average output power of -6 dBm.

Multiple negative differential resistance of InP/InGaAs superlattice-emitter resonant-tunneling bipolar transistor at room temperature

Abstract: Sequential resonant-tunneling behavior of a resonant-tunneling bipolar transistor with five-period i-InP/n-InGaAs superlattice emitter has been demonstrated. An interesting multiple negative differential resistance (NDR) phenomena resulting from the creation and extension of the high-field domain in a superlattice is observed at room temperature. Furthermore, the employing of a thin n-InGaAs emitter layer between an InP/InGaAs superlattice and p+-InGaAs base layer helps to lower the potential spike at the base–emitter junction and the reduce neutral–emitter recombination current. Experimentally, transistor performance, incorporating multiple NDR, with a relatively large current gain of 454 and an offset voltage as low as 80 mV, is achieved.

Voltage-controlled oscillator, frequency synthesizer, and communication system

Abstract: PROBLEM TO BE SOLVED: To provide a voltage-controlled oscillator which has a wide variable frequency range and generates little phase noise. SOLUTION: The voltage-controlled oscillator is provided with: a resonance circuit 70 consisting of a reactance control part 52 whose reactance is controlled with a control voltage, a phase adjustment part 54 coupled with the reactance control part 52, and a piezoelectric thin-film resonator 56 coupled with the phase adjustment part 54; and a negative resistance circuit 60 which drives the resonance circuit 70 and has a positive reactance increment at an oscillation frequency in a stationary state with respect to the reactance at an oscillation frequency in oscillation actuation. The piezoelectric thin-film resonator 56 has a series resonance frequency higher than the oscillation frequency in the stationary state. COPYRIGHT: (C)2005,JPO&NCIPI

Tunnel diode oscillator applied as sensor-modulator for telemetry of temperature in human beings and animals

Abstract: The purpose of this study was to use the tunnel diode in order to evaluate objectively the temperature in human beings and animals based on the region of negative resistance of the tunnel diode, we have designed and developed a relaxation tunnel diode oscillator circuit (astable) that acts as sensor and modulator of its oscillation frequency. The modulated signal corresponding to the temperature is transmitted by radio telemetry in FM. The prove of the system was carried out in animal test (rat), where the tunnel diode (sensor-modulator) was implanted. The range of temperature of the tunnel diode as a sensor of temperature was characterized of 0 /spl deg/C to 50 /spl deg/C with a resolution of 0.03 /spl deg/C and an accuracy of /spl plusmn/0.1 /spl deg/C. Additionally, measurements of temperature of the human skin using the same tunnel diode were obtained.

Low power RFICs for receiver applications - design and performance issues

Abstract: This paper consider two important low-power radio frequency integrated circuits (RFICs) for receiver applications - mixers and oscillators The performance of a mixer when the transistor's body terminal is used as one of the inputs is considered It was observed that this topology allows the use of lower supply voltages compared to conventional Gilbert Cell mixers In the case of the oscillator, the effects of hot carriers on the performance of a LC-tank negative resistance oscillator was studied The important effects are a drop of oscillation amplitude and a slight increase in frequency Also, the effects of fluctuations in the transistor's channel length on the oscillator performance are investigated The use of body bias is proposed as a means to compensate for changes in the performance characteristics due to these fluctuations

Impedance measurements of stainless different heat treated steels in the active - passive region

Abstract: The behaviour of differently heat-treated X20Cr13 steels in 0.1 M H 2 SO 4 was studied using the classical potentiodynamic method and electrochemical impedance spectroscopy. On the base of the potentiodynamic curve the constant potentials have been chosen at which the impedance spectra were recorded: at the active peak, the potential next to the active peak and in the active - passive region. All impedance spectra show typical shapes: the high frequency portions have typical semicircular shapes of complex plane plots, whereas at low frequencies the plots deviate into semicircles running in opposite direction and yielding the so-called negative resistance as the frequency approaches 0 Hz. These spectra are interpreted in terms of a model by R.D. Armstrong describing, in a general way, the electrochemical reaction at interfaces with adsorbed intermediates. Applying the model to the measured impedance spectra, we have been able to distinguish between the cases in which the observed charge transfer resistance is solely determined by nature of metal surface and the cases in which, beyond this inherent metal property, the charge transfer is determined by the degree of surface coverage with adsorbed intermediates. For example, while the oil-quenched X20Cr13 steel shows the lowest inherent charge transfer resistance of bare surface, the air-quenched sample exhibits the largest resistance due to surface passivation by intermediates. All results of impedance analysis are well-correlated to the measured potentiodynamic curves.

A novel application of resonant tunneling devices in high performance digital circuits

Abstract: Resonant tunneling devices have been used in various digital circuit applications to improve packing density, circuit speed, as well as power consumption. In this paper, we describe a new class of applications of using those quantum tunneling devices in digital circuit design. More specifically, we have developed a strategy to use RTDs in conjunction with CMOS logic circuits that leads to new circuits that have elevated noise immunity. The proposed method utilizes RTD's negative differential resistance property and the fact that they have very high speed index. We have shown through simulation that the proposed circuits have increased noise immunity yet they retain all the advantages of CMOS dynamic circuits. The benefit of the proposed circuits is still evident using currently available silicon-based RTD's with a relatively small peak-to-valley current ratio.

Equivalent inductor circuit

Abstract: PROBLEM TO BE SOLVED: To provide an equivalent inductor circuit without a negative resistance component in the impedance even when an input signal is in a high frequency region. SOLUTION: The equivalent inductor circuit has a capacitor C1, a gyrator constituted by a plurality of operational transconductance amplifiers 1 and 2 having the capacitor C1 as a load, and a resistor R1 for suppressing a negative resistance component in the impedance within a used frequency band and being connected in series to the capacitor C1.

Design of K-band Voltage-controlled Oscillator with GaAs MESFET

Abstract: This paper presents the design of a Kband VCO using GaAs metal semiconductor fieldeffect transistor(MESFET)as active deviceA 100 MHz continuous tuning bandwidth is achieved with an output power of 2 mWThe center of oscillator frequency bandwidth is 2056 GHzThe phase noise level of90 dBc/Hz for offset frequency of 100 kHz is measured at 2056 GHzThe VCO is proved by simulation and experiment results

Piezoelectric oscillation circuit

Abstract: PROBLEM TO BE SOLVED: To provide a piezoelectric oscillation circuit which oscillates at a desired resonance frequency even if a resonance circuit has a capacitive near the desired resonance frequency. SOLUTION: A resonance circuit 1 comprises a SAW resonator SAWR having a capacitive, a capacitor Cs connected in parallel to the SAW resonator SAWR, and an inductor Ls connected in series to a parallel circuit of them. An amplification circuit 2 is provided with a transistor Tr showing negative resistance, a capacitor C1 for feedback connected between the base and the emitter, and a capacitor C2 connected between the emitter and the earth, and the base of the transistor Tr is connected to the inductor Ls of the resonance circuit 1. By this configuration, the phase of impedance of the resonance circuit 1 viewed from the amplification circuit 2 is rotated due to the inductor Ls to make the resonance circuit 1 inductive though the SAW resonator SAWR has a capacitive. COPYRIGHT: (C)2005,JPO&NCIPI

S-Parameter measurements for determination of the impedance of IMPATT diodes in dependency on the current density

Abstract: S-parameter measurements were performed to characterize IMPATT diodes integrated in coplanar waveguides, up to a maximum frequency of 40GHz. With a de-embedding procedure the real- and imaginary part of the impedance of the inner diodes were calculated. Above the avalanche frequency the diodes showed the expected negative real- and imaginary parts of the impedance. Due to theory, with increasing current density the avalanche frequency shifted to higher values. To manufacture the diodes and oscillators a complete monolithically integrated process was used. This process avoids the use, of heatsinks and the difficult and time consuming bonding process.