Showing papers on "Negative resistance published in 1998"

Varactor tuned microstrip line resonator and vco using same

Abstract: A low noise, wide tuning bandwidth, voltage controlled oscillator employs a resonator circuit formed from at least two microstrip lines (42, 44) which are electromagnetically coupled to one another. Each of the microstrip lines (42, 44) has one end electrically coupled to circuit ground to provide a substantially inductive resonator circuit which is substantially immune to parasitic end effects and radiation losses. The frequency of the voltage controled oscillator is controlled by a variable capacitance varactor diode (43) coupled to at least one of the microstrip transmission lines (42). The resonator circuit (42, 43, 44) is well suited for use with a bipolar transistor (70) configured as a negative resistance oscillator.

Voltage controlled oscillator circuit capable of switching between oscillation frequency bands

Abstract: A voltage controlled oscillator circuit using a negative resistance section (-R) for supplying electric power to the voltage controlled oscillator circuit and parallel resonance of the capacitance and the inductance of the circuit comprises a first variable capacitance diode (D1) and a second variable capacitance diode (D2) which are connected in parallel. The first variable capacitance diode (D1) varies its capacitance according to a first control voltage (Vband) and thereby varies oscillation frequency (f0) of the voltage controlled oscillator circuit. The second variable capacitance diode (D2) varies its capacitance according to a second control voltage (Vcont) which is independent of the first control voltage (Vband), and thereby varies oscillation frequency (f0) of the voltage controlled oscillator circuit independently. Coupling condensers (C1, C2) are provided between the negative resistance section and the first variable capacitance diode (D1), and between the first variable capacitance diode (D1) and the second variable capacitance diode (D2), in order to cut direct current off. According to the voltage controlled oscillator circuit, variable range of oscillation frequency can be remarkably enlarged and digitally switching the oscillation frequency between oscillation frequency bands is made possible.

A 1.8 GHz CMOS quadrature voltage-controlled oscillator (VCO) using the constant-current LC ring oscillator structure

Abstract: A new fully integrated CMOS quadrature voltage-controlled oscillator (VCO) realized in a standard 0.5 /spl mu/m double poly double metal (DPDM) CMOS technology is proposed, that combines a fully differential two-stage ring oscillator with LC tanks and negative resistance to provide both in-phase and quadrature output signals. The phase noise is low due to the use of the resonator-type oscillator. The simulation results show that with an on-chip varactor tuned resonator and a control voltage of 0-3 V, the tuning range of the VCO is 160 MHz from 1.67 GHz to 1.83 GHz. Under 1% mismatch of the inductor or capacitor, the phase errors of VCO outputs are less than 1/spl deg/ from perfect quadrature and the amplitude ratio are less than 1.0007. The power dissipation is 35 mW for 3 V power supply. The area is 1.3/spl times/0.9 mm/sup 2/, dominated by the two integrated spiral inductors.

Systematic realization of low-frequency oscillators using composite passive-active resistors

Abstract: A systematic method for realizing low-frequency oscillators is described. The method is applicable to any simple harmonic oscillator configuration and is based on replacing a selected passive resistor with a composite passive-active resistor. Two possible configurations for the composite resistor are discussed. The classical Wien-bridge oscillator is then modified using one of these configurations. PSPICE circuit simulations and experimental results are included.

Proposal of low-noise amplifier utilizing resonant tunneling transistors

Abstract: A low-noise amplifier utilizing the negative input resistance of resonant tunneling transistors (RTT's) is proposed. Expected features of the RTT amplifiers are: 1) negligible effect of noise sources at the output, owing to their large power gain; 2) flat variation of noise figure (NF) versus frequency, due to white spectra of noise sources at the input; and 3) a high maximum oscillation frequency (f/sub max/) (over several 100 GHz), Based on simulated DC characteristics, over 500 GHz f/sub max/ and 0.3 dB NF at 100 GHz are predicted for optimized AlGaAs/GaAs/AlGaAs resonant tunneling diodes (RTD's). In an RTT formed by coupling an FET to an optimized RTD, 0.55 dB minimum noise figure and 26 dB associated gain are predicted at 100 GHz. Also, a 1/w/sup 2/ spectrum of the input noise resistance is predicted at low frequencies.

Photo-induced electro-optic oscillator using a multiple quantum well pin diode

Abstract: A photo-induced electro-optic oscillator using a multiple quantum well structure PIN diode using a negative resistance characteristic of a photocurrent-voltage is disclosed. The present invention can generate the modulated optical signal as well as the electrical AC signal of a high output by using the multiple quantum well structure having the electro-absorption as the intrinsic layer of the PIN diode, regulate the electrical AC signal frequency and signal amplitude by means of regulating the PIN diode and electrical elements, regulate the modulated optical signal frequency and the modulated signal difference and extinction ratio by means of regulating the multiple quantum well structure, as a result, to generate the electrical and optical signal of a high output, high frequency.

Power source device for sputtering, and sputtering device using the device

Abstract: PROBLEM TO BE SOLVED: To stably generate a magnetron discharge under pressure showing the characteristics of negative resistance on a sputtering source under a pressure lower than the discharge starting pressure, and to stably execute sputtering by controlling the electric current to be outputted from a constant current circuit by a control circuit. SOLUTION: A control part 26 for a sputtering device starts a vacuum pump 22 and evacuater a vacuum tank 22, and gaseous Ar filled in piping 24 is flowed into a pulse shape by the operation of a valve. By the signal of the control part 11, the negative voltage of a d.c. power source 12 is applied to a sputtering source 21 to generate magnetron discharge. The control part 11 allows a transistor Z1 to intermetently be on, and the output of the d.c. power source 12 is applied to a choke coil L. In the midst in which normal magnetron discharge is generated in the vacuum tank 22, an electric current flowing in the a constant current circuit is detected by a current detector 14, the duty ratio of a switching signal S1 by which the control of and off on the transistor Q1 is executed so as to make the detected electric current certain is made variable, and a certain electric current is made to flow.

A low-power monolithic GaAs FET bandpass filter based on negative resistance technique

Abstract: This paper describes a monolithic GaAs FET active bandpass filter utilizing negative resistance elements. The negative resistance element was realized with a common-drain FET with series inductive feedback and the measured output impedance characteristics are given. The fabricated monolithic fourth-order filter showed an insertion loss of 0.7 dB at 4.85 GHz and a 3-dB bandwidth of 50 MHz with a DC power consumption of 7.5 mW.

Integrated semiconductor device having negative resistance

Abstract: A memory cell of an SRAM includes an access transistor, and an MIS switching diode. The access transistor has a drain electrode connected to a bit line of a corresponding column, a source electrode connected to a storage node, and a gate electrode connected to a word line of a corresponding row. The threshold voltage of the access transistor is small than the threshold voltage of a bit line load transistor. The MIS switching diode is connected between the storage node and a second power supply potential node. The switching initiate voltage of the MIS switching diode is greater than the difference between the first potential and the threshold voltage of the bit line load transistor, and smaller than the difference between the first potential and the threshold voltage of the access transistor. Thus, data can be read/written and held accurately.

Contactless electronic switch with externally influenceable oscillator

Abstract: The device includes an oscillator which comprises a loop formed of a coil (S) and a capacitance (K). A negative resistance circuit comprises a first branch formed of a first resistor (R1), the collector-emitter path of a first transistor (V1), the collector-emitter path of a second transistor (V2), and the oscillator loop. A second, parallel branch is formed of a second resistor (R2), the collector-emitter path of a third transistor (V3), the collector-emitter path of a fourth transistor (V4), and a fourth resistance. The bases of the first and third transistor are properly biased and connected together at a first point (13), and the bases of the second and fourth transistor are properly biased and connected together at a second point (14). A third resistance (R3) is connected across the first and second point. A supply voltage (U0) feeds the circuit over a fifth resistance (R5).

Voltage controlled piezoelectric oscillator

Abstract: PROBLEM TO BE SOLVED: To prevent oscillation from stopping and to obtain an oscillator wide in frequency variable range by making at least, one of division capacitances into a variable capacitance diode thereby changing negative resistance at a variable capacitance diode side together with a control voltage and making the absolute value of negative resistance larger than the effective resistance of crystal at all times. SOLUTION: The capacitance corresponding to the division capacitance of a conventional voltage controlled crystal oscillator is replaced by a circuit in which the capacitance C5 is connected in series to the parallel circuit of the variable capacitance diode D3 and the capacitance C8 and the circuit in which the capacitance C6 is connected in series to the parallel circuit of the variable capacitance diode D4 and the capacitance 9. Then, the capacitance C5 is connected to the base of a transistor and the variable capacitance diode D4 is grounded. The D.C. bias voltages of the variable capacitance diodes D3 and D4 are respectively applied from Vcont by way of resistance R7 and R9. Thus, the absolute value of negative resistance is held larger than the effective resistance of a crystal vibrator even when a load capacitance is reduced in accordance with the control voltage and the oscillation is prevented from stopping.

A Novel Broad-Band MMIC VCO Using an Active Inductor

Abstract: This paper proposes a novel broad-band MMIC VCO using an active inductor. This VCO is composed of a serial resonant circuit, in which the capacitor is in series with an active inductor that has a constant negative resistance. Since the inductance value of this active inductor is inversely proportional to the square of the transconductance and can vary widely with the FETs gate bias control, a broad-band oscillation tuning range can be obtained. Furthermore, since this active inductor can generate a constant negative resistance of more than 50 Ω, the proposed VCO can oscillate against a 50-Ω output load immediately without using additional impedance transformers. We have fabricated the VCO using a GaAs MESFET process. A frequency tuning range of more than 50%, from 1.56 to 2.85 GHz, with an output power of 4.4±1.0 dBm, was obtained. With a carrier of 2.07 GHz, the phase noise at 1-MHz offset was less than −110 dBc/Hz. The chip size was less than 0.61 mm^2, and the power consumption was 80 mW. This broad-band analog design can be used at microwave frequencies in PLL applications as a compact alternative to other types of oscillator circuits.

Crystal oscillator circuit with crystal reducing resistance and integrated circuit therefor

Abstract: A crystal oscillator circuit includes a CMOS invertor having an input terminal and an output terminal, a crystal resonator connected between the input terminal and the output terminal respectively at a first connection node and a second connection node, and a feedback resistor connected between the input terminal and the output terminal of the CMOS invertor. A first capacitor is provided between the first connection node and a power source terminal at a predetermined potential and a second capacitor is provided between the second connection node and a power source terminal at the predetermined potential. At least one resistor is disposed in series with at least one of the first capacitor and the second capacitor and has a resistance so as to limit a crystal current in the crystal resonator while maintaining negative resistance for stable oscillation. In an embodiment, a resistor is provided in series with each capacitor. Furthermore, an embodiment of the invention includes an integrated circuit permitting the above circuit structure with the crystal resonator and first and second capacitors accommodated external of the integrated circuit. Alternatively, the first and second capacitors may be accommodated on the integrated circuit.

Effect of Current Density on the Series Resistance of SDR (n+np+) Silicon IMPATT Diode in the X Band

Abstract: The variation of the electrical series resistance with the experimental operating bias current densities have been simulated using a realistic computer analysis of n + np + Si IMPATT diode of the type HP 5082-0432 of capacity 0.02 pF based on the dc and small signal properties in the X band. The spatial distribution of the negative resistivity along the depletion layer has been plotted at the experimental operating conditions. The results for the series resistance fit well with the device data and it is observed that the value of series resistance decreases negligibly although the diode operating frequency increases with the increase of the bias current.

Appearance of negative resistance in p - n junction structures in a microwave field

Abstract: The results of theoretical and experimental investigations of the appearance of negative differential resistance in p-n junction diode structures in the presence of a high level of microwave power are presented. The theoretical analysis of the influence of a high level of microwave power on the form of the current-voltage characteristic of a diode takes into account the variation of the constant component of the current flowing through the p-n structure due to the heating of the free charge carriers and the rectifier effect.

Temperature stabilized oscillator and proximity switch including the same

Abstract: PROBLEM TO BE SOLVED: To easily stabilize the temperature dependence of an oscillator, and to manufacture a proximity switch having a large switching distance which stably functions across a wide temperature range. SOLUTION: In an oscillator, including a resonance circuit L, C, RCU and an amplifier circuit V, R1 , R2 , R3 connected as a negative resistance Rn , a DC source I1 is serially connected with the resonance circuit L, C, RCU. Thus, currents UCU being the scale for the resistance of an oscillator circuit coil L can be obtained. A control circuit V1 , M ; V2, V3 , M controls a negative resistance Rn inversely proportional to the resistance RCU of the oscillator circuit coil L by using this signal UCU.

Interrogator for semi-passive transponder tags

Abstract: An interrogator circuit 2 for use with semi-passive transponders 30 (which reflectively modulate transmitted signal 28) has a transistor 8 which self oscillates to radiate power 28 from patch antenna 4. The transistor simultaneously acts as a self oscillating mixer producing an output 40 representative of the modulated signal 32 received at antenna 4. Bias and matching networks 12, 14 including microstrip lines 16, 26 ensure that the FET 8 operates as a negative resistance. FET 8 is coupled to the antenna by a matching network 6 comprising microstrip line 10. In a small signal condition at start up the reflection gain of FET 8 is greater than the reflection coefficient of antenna 4 so that any signal at gate g will be reflected with increased magnitude. When the circuit 2 reaches a stable oscillatory condition, the reflection gain of FET 8 equals the return loss of antenna 4. The interrogator may modulate the transmitted signal 28 by modulating the FET drain-source current. The frequency of oscillation of the circuit is determined by the resonant frequency of the antenna. A fine tuning circuit 42 comprising an additional patch antenna element 50 enables accurate frequency setting by adjustment of bias voltage V bias .

Negative resistance circuit for monolithic resonators using gate-to-source resistive feedback

Abstract: A simple negative resistance circuit is developed for a resonator using a resistive feedback between the gate and source terminal of a GaAs MESFET. The input conductance can be varied by a change of feedback resistor with small DC power consumption. The Q factor of the resonator is nearly 250 and shows a wide dynamic range.

Study and characterization of a new MOSFET voltage controlled negative resistance for super selective IC tank circuits

Abstract: MOSFET transistors may be fabricated with a variety of gate geometries. The trapezoidal shape provides new interesting one. If this nonstandard geometry is made dependent on the biasing condition, original behavior and new I-V characteristics are expected to be obtained. This paper presents a study and characterization of this new device and shows that it provides a voltage controlled negative resistance. It is seen to have many noticeable advantages over those devices which are already known. This new negative resistance find a wide areas of applications in communications, measurements and instrumentation. It can be used to build up a super selective tank circuits which can be entirely integrated using MOSFET technology.

Series Connection of Resonant Tunneling Diodes for Eliminating Spurious Oscillations

Abstract: Resonant tunneling diodes, which have the highest operating frequencies among solid-state oscillating devices at millimeter and submillimeter wave frequencies, generate spurious low-frequency oscillations easily. As a method of suppressing spurious oscillation of negative resistance devices, the oscillation devices may be connected in series. In this paper, this approach is applied to resonant tunneling diodes. If two diodes are connected in series, no spurious oscillation is observed in the oscillation output spectrum. The effect of suppression of spurious oscillation is experimentally confirmed. Further, from the output characteristic, it is found that the devices are useful as low-noise high- frequency amplifiers and frequency multipliers. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(12): 17–25, 2001

Method and circuit for reducing noise of pll oscillation circuit

Abstract: PROBLEM TO BE SOLVED: To provide a method/circuit for reducing the harmonic noise of an oscillation circuit. SOLUTION: A lock detector 8 detecting a lock state from the output of a phase comparator 5, a D-flip flop 9 outputting a high level signal from a lock detection signal D being the detecting signal, a clock TnQ and the starting control signal PS of PLL and a current source 10 stopping current to an oscillation circuit 7 to which the high level signal is inputted are provided. The oscillation circuit 7 sets the negative resistance |-Rn| of the circuit to a high gm value which is 3-10 times as much as the equivalent resistance Re of a crystal oscillator at the time of starting. When current from the current source 10 is stopped, the gm value is reduced as |-Rn|=Re. Thus, the occurrence of harmonics is suppressed and noise is reduced.

Simulations of signal amplification and oscillations using a SNS junction

Abstract: A Superconducting - Nonnal metal - Superconducting junction (SNS junction) may exhibit a Low Voltage Negative Differential Resistance (LVNDR) effect over part of its Current Voltage Characteristic (CVC) As the LVNDR effect is stable against a bias voltage at this CVC range, it should be possible to combine a SNS junction with conventional electronic circuits to obtain electronic devices such as mixers, amplifiers and oscillators Making use of this remarkable effect, we show that an amplifier may be feasible by assembling a simple voltage divider made up of a SNS junction in series with a resistor The amplifier circuit includes an adjustable DC voltage supply (the bias voltage) and an AC signal source with a given voltage The SNS junction is connected in series with a resistor R Choosing values of the load resistance R approximately equal to the module of the negative differential resistance (dV/dI), at the bias voltage, we may obtain large gains in this amplifier device In order to get an oscillator, the SNS junction should be connected to a RLC tank circuit with a bias voltage adjusted in the range of the LVNDR region of its CVC A power output of the order of one microwatt may be easily obtained

Crystal oscillator circuit and integrated circuit device for crystal oscillation

Abstract: PROBLEM TO BE SOLVED: To reduce the current flowing through a crystal resonator in a crystal oscillator circuit. SOLUTION: The current flowing through the crystal resonator is reduced by providing resistances Rd and Rg on one of the paths formed of the output terminal, capacitor element Cd, and power terminal VDD of a CMOS inverter 2 and one of the path formed of the input terminal, capacitor element Cg, and power terminal VDD of the CMOS inverter 2. Specially, the crystal current is reduced and necessary negative resistance is obtained by setting the sum of the values of the resistances Rd and Rg to 10 to 320 Ω. COPYRIGHT: (C)1999,JPO

Negative resistance amplifier

Abstract: PROBLEM TO BE SOLVED: To provide a negative resistance amplifier of high gain, low noise and a wide band which is excellent in unilateral property of a signal. SOLUTION: A negative resistance transistor having a negative input conductance in which resonance tunnel effect is used from a field effect transistor structure and a resonance tunnel diode structure or a bipolar transistor structure and a resonance tunnel diode structure, etc., is constituted. When the negative resistance transistor is subjected to cascade connection to a signal source, setting is made to lead a relationship of 0 0) is conductance allowing for a signal source form a boundary surface, -gi (gi >0) is input conductance of a negative resistance transistor and G is a specified conductance value (G

High-frequency amplifier

Abstract: PROBLEM TO BE SOLVED: To reduce a packaging space of an abnormal oscillation preventing circuit that prevents abnormal oscillation which is caused by out-of-band negative resistance of a high-frequency amplifier. SOLUTION: This device consists in parallel of a single plate condenser 7, and a connection wire 8 to a direct current cut filter 4 that is provided at a gate output of a high-frequency amplifier, and connects in parallel a serial resonance circuit which makes a serial resonance frequency a frequency that generates negative resistance. The impedance of a circuit, where the serial resonance circuit and the filter 4 are connected in parallel is made low impedance in a frequency out-of-use band and high impedance in a frequency within a use band.

Design and fabrication of GaAs OMIST photodetector

Abstract: We designed and fabricated GaAs OMIST (Optical-controlled Metal-Insulator-Semiconductor Thyristor) device. Using oxidation of A1As layer that is grown by MBE form the Ultra-Thin semi-Insulating layer (UTI) of the GAAS OMIST. The accurate control and formation of high quality semi-insulating layer (AlxOy) are the key processes for fabricating GaAs OMIST. The device exhibits a current-controlled negative resistance region in its I-V characteristics. When illuminated, the major effect of optical excitation is the reduction of the switching voltage. If the GaAs OMIST device is biased at a voltage below its dark switching voltage V-s, sufficient incident light can switch OMIST from high impedance low current"off"state to low impedance high current "on"state. The absorbing material of OMIST is GaAs, so if the wavelength of incident light within 600 similar to 850nm can be detected effectively. It is suitable to be used as photodetector for digital optical data process. The other attractive features of GaAs OMIST device include suitable conducted current, switching voltage and power levels for OEIC, high switch speed and high sensitivity to light or current injection.

Contactless electronic switch

Abstract: A switch contains an oscillator circuit (2) as shown in figure 1 with a negative resistance connected in parallel to the oscillating circuit (K, S), enabling the use of an oscillator coil (5) with only two connections. This oscillator coil (5) is relatively easier to manufacture than the tap-fitted coils generally used until now, and its function is not affected when the connections are mistakenly exchanged.

Behaviour of a stable welding arc with positive and negative arc resistance

Abstract: The dependence of the voltage of a stable plasma arc on the current, arc length and pressure has been fitted to experimental data with the arc operating in positive and negative resistance modes. A general justification for this behaviour is provided together with the operating domain over which negative resistance behaviour can be observed. A simplified mathematical model is provided to describe the negative resistance mode of operation of the arc neglecting conduction and radiation heat losses but retaining axial convection.

Effects of drain current kinks and negative gate resistances on the performance of HFET MMIC power amplifiers

Abstract: Using novel characterization techniques, frequency-sensitive gain/phase discontinuities of multi-stage MMIC power amplifiers were correlated with HFET drain current kinks and negative gate resistances. The correlation was explained in terms of hole-trapping and self-biasing mechanisms. A remedy involving bias-stabilization diodes was experimentally verified. Other possible remedies are also discussed.

DC and AC Characteristics of GaAs/InGaAs/AIGaAS Real Space Transfer Transistors

Abstract: DC and AC performances of a GaAs/InGaAs/AIGaAs negative resistance field-effect transistor (NERFET) are demonstrated by molecular beam epitaxy (MBE) for the first time. The negative differential resistance (NDR) resulted from the observation of the hot electron real space transfer effect in InGaAs channel. By Hall measurements, the structure shows carrier mobility as high as 4300 (13500) cm2/v-s at 300 (77)K, which is suitable for high frequency operation. For DC performance, the largest peak-to-valley current ratio of the device is about 5 at room temperature. For AC performance, S-parameter measurements of high frequency and microwave characteristics indicate a projected maximum frequency of oscillation of fmax⁡=2.7GHz and a current gain cutoff frequency (fT) occurs at 1.8GHz.