Improved crosscoupled multivibrator controllable in frequency over a wide range

An improved crosscoupled multivibrator is described which can be continuously varied in frequency over a wide range (considerably in excess of 100 to 1 with an upper frequency of 10 MHz). The circuit can operate from a 5 V supply line, and therefore it is ideal as a clock generator for logic elements because a common power supply can be used.     

High frequency wide range CMOS analogue multiplier

A new CMOS analogue cell which can be used to implement a four-quadrant multiplier circuit is introduced. Simulation results of the circuit using the MOSIS 2 mu m process parameters are given. The circuit has an input range of +or-4 V and linearity error less than 1% for inputs up to +or-3 V. The magnitude and phase response are very flat; even at 30 MHz the change in the magnitude is less than 0.086 dB (1%) and the phase shift is less than 5 degrees .<>     

A CMOS circuit for evaluating the NBTI over a wide frequency range

In this paper an application specific integrated circuit (ASIC) for evaluating the NBTI effects over a wide frequency is described. The circuit is designed to allow measurements in multiple modes, specifically, DC and AC NBTI, on single pFET and on an inverter. The results indicate that AC NBTI is independent of the frequency in the 1 Hz–2 GHz range. Furthermore, the voltage and the stress time acceleration are identical for both AC and DC NBTI stress.     

New method for determining the permeability tensor of magnetizedferrites in a wide frequency range

To provide a broadband method for measuring the complex permeability tensor components of magnetized ferrites we have realized a nonreciprocal rectangular waveguide cell. A network analyzer setup is used to measure the scattering parameters of the cell over a wide range of frequencies. The nonreciprocity of the cell permits the determination of the permeability tensor components in a single experimental phase. Complex permittivity and complex components of the permeability tensor are computed from a data-processing program, taking into account higher order modes excited at the cell discontinuities and using a numerical optimization procedure to match calculated and measured values of the S-parameters. We have studied the convergence of the calculated S-parameters as the number of modes taken into account in the calculations. Sensitivity to the input parameters for the optimization algorithm is discussed. A thru-reflect-line calibration in conjunction with a specific sample holder is used to eliminate systematic errors inherent in the S-parameter measurements. Measured complex permeability tensor components data for microwave ferrites are presented at X-band frequencies (8-12 GHz). Experimental results are in good agreement with theoretical results given by the ferromagnetic material theory     

Automatic measurement of complex tensorial permeability ofmagnetized materials in a wide microwave frequency range

This paper describes a microwave measurement technique enabling the automatic and broad-band determination of the complex permeability tensor components μ, κ of magnetized materials. The method is applicable to ferrites, as well as magnetic composite materials. The measurement cell is composed of a nonreciprocal strip transmission line partly filled with the sample that is to be characterized. The data-processing program based on a quasi-static approach is valid whatever the magnetization state of the material is from the total demagnetization state to the saturation. The scattering matrix of the cell is measured in a wide frequency range (130 MHz-6 GHz) with a network analyzer setup. The stripline is set in the air gap of an electromagnet to magnetize the material. The electromagnetic parameters of the sample under test are deduced from the scattering matrix using analytical relations. General equations for μ and κ are proposed. Some measurements of magnetized ferrites are reported and compared with values predicted by Polder's relations to validate the technique in the saturation state. To our knowledge, this is the first noniterative measurement method giving μ and κ simultaneously in a wide range of frequency     

一种温度不敏感频率范围宽的三角波振荡器

本文介绍了一种由双比较器型施密特触发器构成的三角波振荡器电路,它通过对电容恒流充放电产生对称三角波;此电路的优点是其产生的三角波的频率稳定且具有很高的精度,并对温度和电源的变化不敏感;文章最后给出了电路的Hspice仿真结果。     

A nonlinear theory of coherent oscillations in a resonance tunnel diode in a wide frequency range

The Schrödinger equation with open boundary conditions was solved numerically; the solutions make it possible to describe the coherent oscillations in a resonance-tunnel diode in a wide range of frequencies and amplitudes of the fields. In an approximation linear in the field and in the adiabatic limit, the results of numerical and analytical calculations coincide with a high degree of accuracy. The dependences of the power of oscillations on the current and the parameters of the resonance-tunnel diode were derived. It is shown that, in the quantum-mechanical mode, oscillations with high power are possible at the frequencies that exceed the level width (i.e., in the terahertz range).     

A wide division-ratio range programmable frequency divider with driving-capability improved

This letter presents an improved architecture of wide division ratio range programmable frequency divider with driving-capability improved. The proposed architecture combines the traditional 2/3 cells and the revised ones to retain the high speed feature and broaden the output duty-cycle. Only less OR and AND gates are added to select the proper output. All of the added circuits are operating at the lower frequency. Thus it enhances the divider’s driving-capability with almost adding no power consumption. This improvement makes it applicable to drive various clocked circuits, which need different frequencies. The presented equation can be used to predict the output duty-cycle with the expected division ratio accurately. Test results show that the output duty-cycle is between 33 and 66%, which corroborate the calculations.     

ESR spectrometer with a wide frequency range using a gyrotron as a radiation power source

The development of a high frequency electron spin resonance (ESR) spectrometer with a wide frequency range using a gyrotron as the radiation power source is described. GYROTRON FU-E, optimized for use in an ESR spectrometer in the millimeter wave range, was developed in Fukui University. In order to test the normal operation of the spectrometer, the ESR of two standard samples, single crystal and polycrystalline DPPH, has been measured, in the pulsed mode over the frequency range from 65 GHz to 135 GHz.     

Study of the loss of the H 11 mode in a modified circular waveguide in a wide frequency range

The specific attenuation coefficient of the hybrid HE ₁₁ mode in a modified circular waveguide is calculated using a method developed earlier. Calculations are performed in a wide frequency range for a number of waveguide diameters. Combinations of the parameters of modified waveguides providing a substantial decrease in the specific attenuation as compared to that in an empty waveguide are determined.     

Innovative test method for the shielding effectiveness measurement of conductive thin films in a wide frequency range

This paper presents an innovative test procedure for the prediction of the shielding effectiveness of small sample materials, consisting of a dielectric substrate coated with thin conducting film, in a wide frequency range up to 8 GHz. The proposed technique overcomes the limitations of the ASTM D4935 test method concerning the upper operating frequency and the required minimum specimen dimensions. A new high-order equivalent circuit model of the test fixture is developed. A correction factor is applied to the measured insertion loss to eliminate both the resonance peak below cutoff appearing in the high-frequency range and the low-frequency errors due to the weak capacitive coupling between the flanges of the coaxial cell. The accurate prediction of the shielding effectiveness of the test material against a plane wave is then derived from the insertion loss measurements.     

A wide locking range and low Voltage CMOS direct injection-locked frequency divider

A low voltage and wide locking range injection-locked frequency divider using a standard 0.18-/spl mu/m complementary metal oxide semiconductor (CMOS) process is presented. The wide locking range and the low-voltage operation are performed by adding an injection nMOS between the differential outputs of the divider that contains on-chip transformers which result in positive feedback loops to swing the output signals above the supply and below the ground potential. This dual-swing capability maximizes the carrier power and achieves low-voltage performance. The measurement results show that at the supply voltage of 0.75-V, the divider free-running frequency is 2.02 GHz, and at the incident power of 0 dBm the locking range is about 1.49 GHz (36.88%), from the incident frequency 3.27 to 4.64GHz.     

A wide frequency range delay line for fast-locking and low power delay-locked-loops

A voltage controlled delay cell with wide frequency range is presented in this paper. The delay-line which is resulted by connecting five series of delay cells generating a wide range of delay from 1.9 to 13.24 ns. It can be used in an analog delay locked loop. The linear characteristic of the circuit with respect to the conventional delay line structures is improved, and a better performance of noise is obtained using differential structure. This circuit is designed by ADS software and TSMC CMOS 0.18 μm technology, with supply voltage 1.8 V. By changing control voltage from 0.335 to 1.8 V in delay line, a wide range of frequency from 75.52 to 917.43 MHz will be covered. Simulation results show that the proposed delay line has power consumption of maximum 3.77 mW at frequency of 75.52 MHz. It also shows that increasing of frequency will reduce power dissipation which is the one of the main characteristics of this novel circuit. Moreover, the delay locked loop which uses these delay cells has a very high lock speed so that the maximum lock time in just five clock cycles.     

Optimal operation of coreless PCB transformer-isolated gate drivecircuits with wide switching frequency range

Gate drive circuits for power MOSFETs and insulated gate bipolar transistors (IGBTs) often require electrical isolation. Coreless printed circuit board (PCB) transformers have been shown to have desirable characteristics from a few hundreds of hertz to a few megahertz and can be used for both power and signal transfer at low-power level. At low operating frequency, the magnetizing inductance has such low impedance that the driving power requirement could become excessive. This paper describes the use of a coreless PCB transformer for isolated gate drive circuits over a wide-frequency range. Based on a resonance concept, the optimal operating condition that minimizes the power consumption of the gate drive circuits is developed and verified with experiments. The coreless PCB transformer demonstrated here confirms a fundamental concept that the size and volume of a magnetic core could approach zero and become zero if the operating frequency is sufficiently high. Coreless PCB transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits and low-power converters. Their sizes can be much smaller than those of typical core-based pulse transformers. The electrical isolation of a PCB is much higher than that of an optocoupler     

Optical properties of fluorite in a wide energy range

The experimental, experimental-calculated, and theoretical spectra of reflectance R, extinction coefficient k, and refractive index n for fluorite crystal are compared in the energy range from 6 to 35 eV. Their important properties and general features are determined. Serious discrepancies between the experimental and experimental-calculated data of R, k, n, as well as between the results of calculations based on five theoretical models, are revealed. The most reliable R spectrum is ascertained. A satisfactory agreement between the experimental-calculated k spectra and the theoretical data for two models is found.     

A clock generator with cascaded dynamic frequency counting loops for wide multiplication range applications

This work presents a clock generator with cascaded dynamic frequency counting (DFC) loops for wide multiplication range applications. The DFC loop, which uses variable time period to estimate and tune the frequency of the digitally controlled oscillator (DCO), enhances the resolution of frequency detection. The conventional phase-frequency detector (PFD) and programmable divider are replaced with a digital arithmetic comparator and a DCO timing counter. The value in the DCO timing counter is separated into quotient and remainder vectors. A threshold region is set in the remainder vector to reduce the influence of jitter variation in frequency detection. The loop stability can be retained by cascading two DFC loops when the multiplication factor (N) is large. The proposed clock generator achieves a multiplication range from 4 to 13 888 with output peak-to-peak jitter less than 2.8% of clock period. A test chip for the proposed clock generator is fabricated in 0.18-/spl mu/m CMOS process with core area of 0.16 mm/sup 2/. Power consumption is 15 mW @ 378 MHz with 1.8-V supply voltage.     

MIS slow-wave structures over a wide range of parameters

Lossy multilayer, multiconductor MIS microstrip structures are analyzed with the spectral-domain approach over a wide range of frequency and substrate loss. The modal attenuation and propagation constants are presented for two- and four-conductor structures as a function of the substrate loss tangent. Single-conductor structures are characterized with contour plots showing the complex effective dielectric constant as a function of both frequency and conductivity. MIS slow-wave structures are analyzed for both Si-SiO₂ and GaAs configurations     

Complex spreading sequences with a wide range of correlationproperties

This paper presents a new family of complex valued pseudo-random sequences for use in coded multiple access communication systems. The family offers a very wide range of values for both auto-correlation (AC) and cross-correlation (CC) functions, allowing great flexibility in the selection of characteristics of sequence sets. Based on the measure described in this paper for the mean-square aperiodic AC and CC values of a set of sequences, the correlation properties of sets of these sequences are compared to well-known sequence sets, and it is shown that sets from the new family of sequences have superior qualities. Tables of parameters for various sequence sets are presented to enable the construction and comparison of sets from this new family     

Very wide range phase-locked loop

A phase-locked loop is described that will capture and lock to any input frequency in the range 1 Hz to 1 MHz without any adjustment. A DC signal proportional to the logarithm of the input frequency is available.