高精度电流检测电阻

在一些电子测量仪器、装置或产品中,经常有测量电路中直流电流的需要,因此研发人员开发出各种各样的电流检测集成电路。它是一种I／V转换器,将测量的电流转换成相应的电压,即V=kI,其中k为比例常数。另外,在一些电子产品中要限制输出电流,以防止有故障时（负载发生局部短路或输出端短路,电源输出电压升高等）产生过流而造成更大损失。检测到有过流发生时,可以控制关断电源或负载开关,或以限制的电流输出。     

Pulse current trimming of polysilicon resistors

The practical application of pulse current trimming of polysilicon resistors has been investigated and successfully implemented in large scale integrated circuit production. In-package pulse current trimming of heavily doped polysilicon resistors allows precise control of the final resistor value and can effectively compensate for process variation in polysilicon sheet resistance. The technique requires no additional process complexity, is layout efficient, remarkably accurate, and is quick and inexpensive from a test perspective. Resistance reduction occurring during the trim process is shown to be reversible to a small, but usable, extent for n-type polysilicon. Thermal modeling of the resistor trim process shows that the peak temperature reached within the polysilicon film must exceed the highest temperature encountered during wafer fabrication before any permanent resistance change occurs. As the resistor is further trimmed, the film temperature approaches the melting point of silicon     

Electrical trimming of ion-beam-sputtered polysilicon resistors byhigh current pulses

Phosphorus doped polysilicon resistors have been fabricated from microcrystalline silicon films which were deposited by ion beam sputtering using an argon ion beam of diameter 3 cm, energy 1 keV and current density 7mA/cm², with a deposition rate of 100-120 Å/min. The resistors, having a sheet resistance of 70 Ω/square and a carrier concentration of 7.5×10¹⁹ cm^-3, were stressed with current pulses of width 10 μs and duty cycle 0.6% for 5 min. There was a steady decrease of resistance with increasing pulse current density above a threshold value 5×10 ⁵ A/cm². A maximum fall of 27% was observed for a 95 μm long resistor. The current-voltage characteristics were also recorded during the trimming process. The trimming characteristics were simulated using a small-signal resistivity model of Lu et al. (1983). and the I-V characteristics by a large-bias conduction model. A close fitting of the experimental data with the theoretical values needed an adjustment of some grain boundary parameters for the different pulse current densities used for stressing. The nature of variation of the grain boundary parameters indicates that the rapid Joule heating of the grain boundaries due to current pulses passivates the grain boundary interfaces, at lower currents above the threshold, and then, at higher values of currents, causes zone melting and gradual recrystallization of the disordered boundary layers and subsequent dopant segregation. It confirms the mechanism suggested in the physical model of Kato et al. (1982). The role played by the field-enhanced diffusivity and electromigration of dopant ions, due to the high instantaneous temperature of the grain boundaries, has also been discussed. The pulse trimming technique is simple and does not cause damage to the adjacent components on a monolithic chip     

Diffused resistors characteristics at high current densitylevels-analysis and applications

Both heavily (source-drain) and lightly (well) doped diffused resistors used in modern CMOS integrated-circuit technologies are studied under high current density levels. The effects of high-field mobility degradation, space-charge limited-current, and charge-depletion narrowing (pinchoff) are discussed, and the related analytical solutions are derived and characterized. The applicability of the study to electrostatic discharge (ESD) protection networks, latchup protection circuitry, and output noise suppression resistors is addressed. Velocity saturation due to mobility degradation is found to be the prevailing mechanism, while space-charge limiting current and depletion narrowing have only limited effect on the lightly doped ones. The resulting saturation current densities allow proper resistor designs which can effectively limit ESD and latchup current into highly susceptible nodes and thus-improve overall circuit reliability, potential suppression of I/O switching noise is also discussed and shown to be more sensitive to the ratio between peak noise and steady-state currents. The experimental data confirm the theoretically predicted saturation velocity and critical field for the lightly doped case but show substantial discrepancy for the heavily doped layer     

1/f noise produced by radio-frequency current in resistors

It has been found that r.f. currents produce 1/f noise in certain resistors. This is of practical importance, because it may well account for the low-frequency noise produced in wideband multicarrier systems, and is of theoretical interest because the prevailing theories on 1/f noise do not predict this noise.     

一种电阻温度补偿电流基准源

本文设计了一种简单的一阶温度补偿电流基准源.主要利用电阻的温度系数与阈值电压VTH温度系数相同的特性实现温度补偿原理.该主体电路采用低压共源共栅(即CASCODE)结构,不需要运放,易于补偿.整个电路采用0.5μm标准CM0S工艺,并用HSPICE仿真分析表明该电路在0～100℃范围内且在工艺变化(容差分析)时基准电流变化不超过3.1%.     

Analogue four-quadrant CMOS multiplier with resistors

The letter will present an integrated analogue four-quadrant multiplier with resistors in CMOS technology. This circuit has a large dynamic range over supply voltages and good linearity, with nonlinearity error less than 2% even when the input voltages are greater than half of the supply voltages.     

CMOS current feedback op amp-based chaos generators using novel active nonlinear voltage controlled resistors with odd symmetrical characteristics

Novel grounded and floating CMOS active nonlinear resistors with odd symmetrical characteristics are designed. The nonlinear resistors are then incorporated into two chaotic oscillator circuits based on a CMOS current feedback op amp (CFOA). The slopes of both the negative and positive segments of the nonlinear characteristics are voltage controlled, allowing for a wide range of dynamic behaviour to be observed and easily tuned in a period doubling route to chaos. Nonlinear current–voltage characteristics are derived in a piecewise-linear form and shown possibly to be modelled using a cubic polynomial approximation. PSPICE simulations using a standard 2.0 μm technology file and numerical simulations of the derived chaotic mathematical models are included.     

An electrical resistance switching network with fixed resistors

A network of 72 fixed value resistors is presented in a parallel series configuration. Each resistor has an accompanying switch which can connect or disconnect the resistor from the network. The question is then which of the 72 switches should be switched on or off to meet a specified total network resistance value. This 72 variable nonlinear zero-one programming problem is solved using a new solution technique called multi-stage Monte Carlo optimization, after appropriate transformations have boon made.     

Active bandpass network with only resistors as passive elements

This letter describes a technique which employs the lowpass properties of transistors to realise a high-Q factor selective amplifier with optimum sensitivity. It requires only resistors as passive elements and transistors as active devices. The realisation of the circuit is optimally insensitive to variations in the gain of transistors and provides for independent adjustment of the amplifier Q factor.     

Environmentally sustainable composite resistors with low temperature coefficient of resistance

Temperature coefficient of resistance (TCR) of thick film resistors are based on fired conducting grains and glass composites. Many analog sensor and control circuits require low (<100 ppm/°C) TCR value. To prepare resistors with low TCR value, knowledge of processing conditions and conduction mechanism parameters are of particular importance because TCR is finalised during firing and cannot be trimmed in the latter stage to a target value as resistors can be. This paper reports the preparation and properties such as microstructural and electrical in particular to sheet resistance, TCR (hot and cold) of eco-friendly composite resistor paste compositions. Our resistor compositions showed the sheet resistance in the range of 1.18–1.38 KΩ/□ and the hot and cold TCR of the compositions reduced substantially from 360 to 100 ppm/°C and 175 to 60 ppm/°C with the addition of TCR modifier.     

The circular loop antenna multiloaded with positive and negative resistors

Studies are made of both the driving-point impedance and the amplitude and phase distributions of the current in a circular loop which is driven by an arbitrary number of delta-function generators and loaded with an arbitrary number of lumped impedances. The only restriction imposed in the present treatment is that the elements (either generator or load) are spaced at equal intervals of2pib/malong the circumference wheremis the total number of elements andbis the radius of the loop. The numerical calculations include loads with negative resistances in order to take account of loops loaded with an element like an Esaki tunnel diode, with proper precautions against both self-oscillation and switching effects. A study of such precautions is to be considered separately. The experimental results agree quite well with theory except for the larger values ofbeta b. The radiation patterns of the loop antennas withbeta b=1loaded with various resistors were also measured.     

Conductance noise investigations on symmetrical planar resistors with finite contacts

Calculations and experimental results are presented of the voltage fluctuations across a pair of sensor electrodes on a planar resistor. A constant current is passed through another pair of driver electrodes. Three types of geometry are considered which are all invariant for rotations of 90°. Areas of low and high contribution to the voltage fluctuations are calculated assuming homogeneous conductivity fluctuations. The calculation method rests on the sensitivity theorem in electrical network theory. Calculations are in agreement with experimental results.     

Reliability of polysilicon thin film resistors with irreversible resistance transition

In this paper, the results of reliability testing (life testing at 125°C for 2000 h) and failure analysis of polysilicon thin film resistors with irreversible resistance transition are presented and discussed. The results of the life test show that electrical parameters of the polysilicon resistors (resistance before transition, transition voltage and resistance after transition) are satisfactorily stable during the life test. Also, calculated values of the mean time before failure (MTBF) and the mean time to failure (MTTF) on the basis of the life test data confirm that the polysilicon resistors have a satisfactory level of reliability for long-term applications. Finally, the results of failure analysis show that typical failure modes of the polysilicon resistors are open, while the responsible failure mechanism is electromigration of aluminum during the life test at the contact between the aluminum line and polysilicon film.     

Refined model of low-impedance film resistors with a comb-like structure

Using the methods of finite element and conformal mapping, analytical models with low and ultralow resistance of the film resistors of the main types of comb-like (interdigital) structures with an arbitrary ratio between the surface resistivities of resistive and conductive films have been worked out. In the resultant resistance, the resistances of comb-like and connecting electrodes are taken into account, as well as the additional resistance caused by the passage of the current from the conductive to the resistive film and vice versa. The conditions under which an interface between the films can be treated as an equipotential surface are revealed. An equivalent circuit of low-impedance comb resistors, which are used as the sensors of the current in the circuits of stabilization and control, as well as thermal and current protection.     

High-resistivity Zr resistors with Ti barrier layer for NbJosephson circuits

Zr resistors are applied to Josephson integrated circuits in place of Mo because a Zr thin film has about five times the resistivity of Mo. Zr resistors do not need to be protected during etching, unlike conventional Mo resistors, because Zr has much smaller etching rate than Nb. Zr resistors occupy only 25% of a unit cell area. Using Zr resistors reduces the area of the Josephson gate and allows increased circuit integration. Increased contact resistance between Zr and Nb films after annealing at about 350°C was found but suppressed with a Ti barrier. Resistors with a resistance variation throughout a wafer of within ±2.8% were fabricated     

Variations of temperature coefficient and noise in thin Al and Al/Si resistors subjected to high current density

Electromigration (EM) in thin Al and Al/Si resistors was investigated by measuring the effect of the stress on the resistance, the temperature coefficientα, the low-frequency noise spectrum (20 mHz-1 Hz) and, for some Al samples, on the residual resistance atT = 11 K. It was found that the temperature coefficient variations versus the stress time have a different behavior for Al and Al/Si, that is an oscillation in the first part of the life of the sample and decreases in the last one, in the first case, whereas, in the second, only the oscillation was detected. This behavior, observed for the first time, has been modeled by means of the Mayadas theory, by supposing a Gaussian distribution of the reflection coefficient for electrons at the grain boundaries. The measurement of the residual resistance also supports the hypothesis that the behavior ofa andR _o (the resistance value at 273 K) is mainly due to the modification of the grain-boundary structure and cannot be explained by taking in account only the variation of the residual resistivity. Besides, the noise measurements give a further proof that the origin of the 1/fg spectra in thin films subjected to high current density must be ascribed to phenomena occurring at the grain-boundaries which are correlated to the phenomena causing temperature coefficient variations. This work was supported by the Progetto Finalizzato MADESS, CNR, Italy.     

On-die termination resistors with analog impedance control for standard CMOS technology

In this paper, we have designed a new voltage-controlled resistor for the purpose of on-die termination in standard CMOS technology. Current-voltage (I-V) characteristics show that this on-die termination resistor has good linearity across a wide range of gate bias, and is suitable for an analog impedance control technique using a feedback loop. The analog impedance control technique has the advantage of continuous impedance adjustment without interfering with normal data transmission and receiving operations. Experimental I-V characteristics show excellent linearity and are in good agreement with simulations. Measured resistance values are within /spl plusmn/5% over process, temperature, and across die variations.