Comparative logic figure of merit of current high-speed transistors

A CCD split-electrode transversal filter (EPSEF) with analog controlled tap weights is described. The programmable tap weighting utilizes a novel analog multiplier for sampled data, based on charge profiling underneath a resistive gate structure. The EPSEF device concept and the performance data of a prototype filter with eight programmable taps are presented. Applications of the EPSEF in several programmed filter functions and in an adaptive filter system are demonstrated.     

Optimum impurity distribution for minimum base transit time in junction transistors

Considering the effect of field dependent carrier mobility, an optimum impurity doping distribution for minimum base transit time has been obtained using variational methods. It is shown that the exponential doping distribution in the base region offers minimum transit time.     

A figure of merit for digital systems

The product of the signal propagation delay times the average power dissipation has been used as a figure of merit for digital systems in much the same way as the gain times bandwidth product has been used to evaluate and compare devices intended for linear circuit applications. In this paper it is shown that for simple logic systems, the delay × power product can be expressed in the form W = KΔVV_ccC_T, where C_T is the total circuit capacitance, V_cc is the power supply voltage, ΔV is the magnitude of the signal voltage transitions, and K is a constant which is usually determined by the circuit configuration but may depend on the pulse repetition frequency. Some simple logic systems are compared using this figure of merit and the results are discussed.     

A figure of merit for IC packaging

Powering integrated circuits is a compromise between increasing power to increase circuit speed and maintaining high packaging density while satisfying cooling constraints. The optimization of this compromise provides the basis for a packaging figure of merit.     

Power semiconductor device figure of merit for high-frequencyapplications

A figure of merit (the Baliga high-frequency figure of merit) is derived for power semiconductor devices operating in high-frequency circuits. Using this figure of merit, it is predicted that the power losses incurred in the power device will increase as the square root of the operating frequency and approximately in proportion to the output power. By relating the device power dissipation to the intrinsic material parameters, it is shown that the power loss can be reduced by using semiconductors with larger mobility and critical electric field for breakdown. Examination of data in the literature indicates that significant performance improvement can be achieved by replacing silicon with gallium arsenide, silicon carbide, or semiconducting diamond     

A figure of merit for iso-index filter materials

A discussion of materials for dispersive birefringent filters which simultaneously exhibit extremely narrow bandwidths (< 1 Å) and wide fields of view (geq +45degacceptance angle) will be presented in this paper. Two specific types, the iso-index filter and the dispersive birefringent Lyot filter are considered. First, a figure of merit for the filter material is derived. Then the figure is related to the optical properties of the material. From this analysis the dependence of the filter bandwidth on crystal birefringence and optical bandedge characteristics is obtained.     

Figure of merit for integrated bipolar transistors

The maximum frequency of operation, ω_max, which is the frequency of operation when the unilateral power gain goes to zero, and ω_T, the unity current gain-bandwidth product, are used as figures of merit for bipolar transistors. Both of these figures of merit are inadequate for state-of-the-art integrated bipolar devices. This is because ω_max is based on neutralizing the feedback between the transistor output and input circuitry by complex networks which are quite impractical in integrated circuits, and ω_T is obtained with the output short circuited and thus has no relevance to a practical application.In this paper, we argue the case for using ω_PT the frequency at which the power transferred between identical amplifiers goes to unity as a practical figure of merit for the integrated bipolar transistor.     

Improved figure of merit for noise in avalanche photodiodes

The authors propose a new noise figure for avalanche photodiodes (APDs). This new noise figure overcomes the difficulty of estimating the internal multiplication and quantum efficiency in complex APD structures, such as III-V SAM APDs. Measurements of the new noise figure are presented for two commercial SAM APDs and the authors show theoretically that it represents a more complete figure of merit for comparing the performance of one APD with another, and with the ideal     

An appropriate device figure of merit for bipolar CML

The effects of base resistance, base transit time, and junction capacitances play a key role in the propagation delay of high-speed bipolar logic gates. A simple device figure of merit for transistors used in current mode logic (CML) circuits, based on minimum propagation delay, is developed. This delay is derived from the large-signal 3-dB cutoff frequency of the CML gate. Results are shown to be applicable for a wide range of device and circuit parameters     

A figure of merit for signal processing reflector antennas

In recent years a new class of reflector antennas utilizing array feeds has been receiving attention. An example of this type of antenna is a reflector utilizing a moveable array feed for beam steering. Due to the circuitry required to adjust the weights for the various feed array elements, an appreciable amount of loss can be introduced into the antenna system. One technique to overcome this possible deficiency is to place low noise amplifiers with sufficient gain to overcome the weighting function losses just after each of the feed elements. In the evaluation of signal processing antennas that employ amplifiers the standard antenna gain measurement will not be indicative of the antenna system's performance. In fact, by making only a signal measurement, the antenna gain can be made any arbitrary value by changing the gains of the amplifiers used. In addition, the IEEE Standard Test Procedures for Antennas does not cover the class of antennas where the amplifier becomes part of the antenna system. There exists a need to establish a standard of merit or worth for multi-element antenna systems that involve the use of amplifiers. A proposed figure of merit for evaluating such antenna systems is presented.     

A figure of merit for a varactor-tuned microwave oscillator

This note derives a figure of merit for a varactor tuned microwave solid state oscillator. Thu figure of merit is in terms of electronic tuning range and power output normalized to the available power from the untuned oscillator. This enables the varactor which will give the required combination of thorns parameters to be specified in terms of y and f _c.

The figure of merit also shows that a varactor with a large value of the product yf _c maximizes the figure of merit.     

Thermoelectric figure of merit of LSCoO-Mn perovskites

Oxide ceramics with nominal composition of were grown by using the citrate sol-gel method followed by high temperature sintering. The thermoelectric properties were studied in the temperature range between 100 and 290 K. The magnitude of Seebeck coefficient S(T) and electrical resistivity ρ(T) increases with the manganese doping level, reaching maximum values close to and , respectively. On the contrary, the total thermal conductivity κ(T) decreases with the manganese content. The behavior of S(T) and ρ(T) was interpreted in terms of small-pollaron hopping mechanism. From S(T), ρ(T) and κ(T) data it was possible to calculate the dimensionless thermoelectric figure of merit ZT, which reaches maximum values close to 0.12; the structural and morphological properties of the samples were studied by powder X-ray diffraction analysis and scanning microscopy (SEM), respectively.     

Thermoelectric figure of merit of a p-n junction

The thermoelectric figure of merit of a semiconductor p-n junction is calculated in terms of the diode theory taking account of the bipolar thermal conductivity. The thermoelectric figure of merit of a Bi₂Te₃ diode is estimated and it is shown that the Ioffe criterion may be at the same level as the best modern thermoelectric materials but cannot exceed unity.     

A figure of merit for the high-frequency noise behavior of bipolartransistors

In this paper a new figure of merit for high frequency noise behavior for use in the evaluation and development of bipolar silicon process technology is introduced. Basic low noise design rules for optimum transistor biasing and emitter scaling are proposed     

A standby current limited performance figure of merit for deepsub-micron CMOS

The delay time of an inverter or NAND chain at a gate length yielding equal standby current and active current is used as the definition of a maximum Figure of Merit (FOM), FOM_max. The circuit power that occurs under this condition of equal standby and active currents is an equally important measure. This FOM_max technique is particularly useful in characterizing complementary metal-oxide-semiconductor (CMOS) technologies in the deep submicron regime. A knowledge of the exact value of gate length is not necessary to apply the FOM_max methodology. For a fixed supply voltage and gate oxide thickness, node capacitance and transistor drive, and off currents determine the value of FOM_max. The value of gate length at which FOM_max occurs decreases with decreasing supply voltage. FOM_max analysis is applied to the comparison of CMOS technologies using gate oxide thicknesses of 5.7 and 3.8 nm     

Thermoelectric figure of merit for bulk nanostructured composites with distributed parameters

The effective properties of composites whose structure includes nanocontacts between bulk-phase macrocrystallites are considered. A model for such a nanostructured composite is constructed. Effective values of the thermoelectric power, thermal and electrical conductivities, and thermoelectric figure of merit are calculated in the mean-field approximation.