1737 Slices
Medium 9789351382492

CH1-2

Saradindu Panda Laxmi Publications PDF

INTRODUCTION

TO

ASIC

11

Fig. 1.12

1.9 LOOK-UP TABLES

The way logic functions are implemented in a FPGA is another key feature.

Logic blocks that carry out logical functions are look-up tables (LUTs), implemented as memory, or multiplexer and memory.

Figure 1.13 shows these aternatives, together with an example of memory contents for some basic operations.

A 2n – 1 ROM can implement any n-bit function. Typical sizes for n are 2, 3, 4 or 5.

In Fig. 1.13 (a), an n-bit LUT is implemented as a 2n – 1 memory; the input address selects one of 2n memory locations. The memory locations (latches) are normally loaded with values from user’s configuration bit-stream.

In Fig. 1.13 (b), the multiplexer control inputs are the LUT inputs. The result is a generalpurpose “logic gate.” An n-LUT can implement any n-bit function. An n-LUT is a direct implementation of a function truth table.

Each latch location holds the value of the function corresponding to one input combination.

(a)

(b)

(c)

Fig. 1.13. Look-up table implemented as (a) memory or (b) multiplexer and memory

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Medium 9789381159323

pre9-2

Dr. Sangeeta Chaudhary Laxmi Publications PDF

302

PRINCIPLES

OF

ELECTRONICS

For example, if we select the gate-to-source voltage (VGS) equal to (VGS(off)/4), then the value of drain current would be

ID = IDSS [1 – 0.25]2 = IDSS (0.75)2 = 0.56 IDSS

It shows that the drain current is slightly more than one-half of IDSS. But it will bias the JFET close to the mid-point of the curve. The value of the drain resistor (RD) is selected in such a way that the drain voltage (VD) is equal to half the drain supply voltage (VDD). The value of gate resistor

(RG) is chosen arbitrarily large, so that it prevents loading on the driving stage.

(ii) Graphical Method. In graphical method, we draw a self-bias line such that it intersects the transfer characteristic curve near its mid-point. The point of intersection of self-bias line and transfer characteristic curve gives us the required Q-point. After this, read the co-ordinates of the

Q-point. The value of source resistance (RS) is expressed by the ratio of gate-to-source voltage

(VGS) to the drain current (ID).

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Medium 9781845939946

6: Collecting and Detecting, Preserving, Preparing and Rearing

Vacante, V. CABI PDF

6  Collecting and Detecting, Preserving,

Preparing and Rearing

The study and examination of mites, both live and dead, is carried out for identification purposes and/or to gain further knowledge of their bio-ecology. To accomplish these tasks, protocols for collecting, preserving, preparing and rearing the different mite categories and groups of mites have been developed over time. According to their bio-ecology, the study and collection of mites living on plants of economic importance involves the host plant, the soil, supports of a different nature around the plant, and sometimes the three habitats together.

Different analytical tools, such as light microscopy (using the dissecting microscope, phase contrast microscope or Nomarski interference microscope), electron microscopy (using the scanning electron microscope and the transmission electron microscope) and physico-chemical and biochemical methods

(electrophoretic analysis, molecular methods, etc.) can be employed. The aspects of mite collection treated in this chapter do not include sampling techniques and methods for estimating populations, which are covered in Chapter 9, on mite control.

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Medium 9781780647784

24 Weissella ceti

Woo, P.T.K.; Cipriano, R.C. CABI PDF

24

Weissella

ceti

Timothy J. Welch,1* David P. Marancik2 and Christopher

M. Good3

1

US Department of Agriculture Agricultural Research Service, National Center for Cool and Cold Water Aquaculture, Kearneysville, West Virginia, USA;

2

Department of Pathobiology, St. George’s University of Veterinary Medicine,

True Blue, St. George’s, Grenada, West Indies; 3The Conservation Fund’s

Freshwater Institute, Shepherdstown, West Virginia, USA

24.1  Introduction

Weissella species are usually not associated with disease; however, novel strains of Weissella ceti were recently recognized as pathogens for rainbow trout

(Oncorhynchus mykiss). W. ceti was identified in

2007 at a commercial rainbow trout farm in China

(Liu et al., 2009) and later in farmed rainbow trout within Brazil (Figueiredo et al., 2012; Costa et al.,

2015) and North Carolina (Welch and Good,

2013). Genome sequences of representative US and

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02_Chapter

Dr. B.C. Punmia ; Ashok Kr. Jain, Arun Kr. Jain Laxmi Publications PDF

2

ACCURACY

AND ERRORS

CHAPTER

2.1 GENERAL

In dealing with measurements, it is important to distinguish between accuracy and precision.

Precision is the degree of perfection used in the instruments, the methods and the observations.

Accuracy is the degree of perfection obtained.

Accuracy depends on (1) Precise instruments, (2) Precise methods and (3) Good planning.

The use of precise instruments simplify the work, save time and provide economy. The use of precise methods eliminate or try to reduce the effect of all types of errors. Good planning, which includes proper choice and arrangements of survey control and the proper choice of instruments and methods for each operation, saves time and reduces the possibility of errors.

The difference between a measurement and the true value of the quantity measured is the true error of the measurement, and is never known since the true value of the quantity is never known. However, the important function of a surveyor is to secure measurements which are correct within a certain limit of error prescribed by the nature and purpose of a particular survey.

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