Analog electronic circuits are generally offered as a core subject during the third or fourth semester of the second year in a four-year course in the electronics and communication, instrumentation and control, and computer engineering branches. It is an important subject and may be slightly toned down in the electrical, civil, chemical, and information technology branches of engineering. Design of discrete and linear integrated circuits (ICs), digital electronic modules, and electronic instrumentation are some of the obvious areas where knowledge of microelectronic circuits becomes essential. Therefore, it becomes important for students at this level of study to be proficient in electronic circuit analysis and their usage in relevant areas.

There are many fine books on electronic (devices and) circuits. Many of them have combined “devices” and “circuits”; a good practice, but sometimes resulting in the book becoming bulky. The idea here is to provide a text that deals with the fundamentals of analog electronic circuits for those who already have a basic knowledge of electronic devices, like semiconductor diodes, bipolar junction transistors (BJTs), and metal oxide semiconductor transistors (MOSFETs), either as full subject or as an introductory subject. Serious effort has been made in preparing the text so that it is not only as study material for examinations but also emphasizes fundamental concepts without being overly voluminous.

Appendix B

Transistor Biasing

When transistors are used as switches, they operate either in cut off or in saturation mode. Whereas, when transistors are used to amplify small signals, a quiescent operating point is selected somewhere in the middle of the conduction range. The region of the location of a quiescent point depends on the kind of amplifier. For example, an amplifier may be used for maximum voltage and/or current gain, or high input resistance, or power gain. In some applications, an amplifier ought to consume minimum power, especially when it is used with a battery-operated device. After selecting the quiescent operating point, it is also required that it remains stable. If there is some change in the operating temperature or variation in supply voltage, the operating point may change its location. Variations due to the manufacturing tolerance in component values and in transistor parameters also affect the quiescent point. Irrespective of the reason, it is required that the quiescent point should remain located within specified limits.

Three amplifier configurations are commonly used while employing either BJT or FET amplification. The configuration depends on the terminals, out of the three, that is common to the input and the output of the amplifier. These configurations are studied on the basis of their characteristics, such as voltage gain, current gain, input and output resistance, and bandwidth, i.e., the frequency range within which the amplifier operates without any significant reduction in the output waveform. The operating frequency range becomes limited as the voltage gain drops at low and high operating frequencies. Hence, the study of frequency response becomes important.

Key Concepts

• • Phenomenon of global warming and its connection with industrialization

• • Concerns and threats of global warming and climate change

• • Impact of carbon emissions on global warming

• • Initiatives towards reduction of carbon emissions and preventing global warming

• • Concepts of Earth Overshoot Day, sustainable development and net-zero emissions

• • United Nations’ sustainable development goals.

• • Link between energy demand and global warming

• • How to decarbonize the energy system

Introduction

Sustainable development, in recent years, has emerged as one of the most talked-about concepts. What does this term mean, and why has it become so important? The Industrial Revolution, which gained momentum in the 19th century, was a landmark event. It represented the culmination of human efforts of thousands of years. The revolution led to great inventions, making life better and easier. The human efforts involved in day-to-day activities have decreased continuously, and automation has resulted in increased human comfort. All sectors of our life, be it agriculture, transport, and even daily routine work at our homes, have been made easier by this revolution. But these developments have extracted a significant cost, particularly on the environment.

The effect of industrial activities on the environment has been described in a poignant way by @SDGoals. It shows that if we scale down the age of the earth from its actual value of 4.6 billion years to 46 years, then on the same scale human life has been on the earth for about 4 hours only. The Industrial Revolution, on this scale, began only a minute ago, and in that time, we have destroyed more than half of the world's forests.

Key Concepts

• • Importance of energy sector in decarbonization

• • Energy-related SDGs

• • Goal 7: Targets, indicators, progress

• • Goal 11: Targets, indicators, progress

• • Goal 13: Targets, indicators, progress

Introduction

The UN, realizing the importance of preventing damage to the climate and warming of the planet, started working in this area more than 50 years ago. But the real transformation has come after the Paris Agreement and the adoption of SDGs. The climate change challenge was largely absent from the agenda of the countries and considerations in policy formulation in even the most advanced countries in the world. Growing evidence of the threat of global warming led to a change in the approach, with a radical change seen after the declaration of the Paris Agreement and the 17 SDGs.

The most important component of the increased concern over climate change is related to energy. Energy is the dominant contributor to climate change, accounting for a minimum around 60% of total global greenhouse gas emissions, and in fact some studies have shown this share to be more than 70%. All the related key terms in vogue these days, such as ‘low-carbon system’, ‘decarbonization’, ‘net-zero system’, and ‘carbon-neutral system’, have energy at the centre. Irrespective of the solutions adopted and the timelines set by different countries, it is agreed upon by all concerned that transition to a low-carbon climate cannot be achieved without decarbonizing the energy systems.

Key Concepts

• • Steps involved for developing sustainable organizations

• • Case study on a university campus

• • Integration of green sources of energy

• • Implementation of energy efficiency measures

• • Ensuring participation of stakeholders for energy conservation

Introduction

The achievement of SDGs defined under the Paris Agreement requires concerted efforts at the international, national, state, organization, and individual levels. The organizations which follow the principles of sustainable development can serve as a role model for others to follow.

Colleges for higher education and the universities also have an important role to play in achieving the SDGs in general and in the adoption and promotion of green sources of electricity in particular. Goal 4 of SDGs, although, is specific to the availability of quality education to all, but these institutions can play a much broader role in realizing the wide-ranging SDGs. For example, Goal 9: Industry, infrastructure and innovation; Goal 12: Responsible production and consumption; and Goal 13: Climate Action cannot possibly be achieved without the mindful and positive influence of higher education institutions.

More importantly, these institutes need to work on the creation of awareness about the need for sustainable development and SDGs, a crucial requirement for their achievement. The institutes should also make sustainable development an integral part of their future plans. Green and renewable sources of energy like solar PV should be adopted for existing buildings, and these should be made mandatory for the new buildings. The academic institutes, more importantly, should practice on their campuses what they are preaching in the class.

Key Concepts

• " Working of solar PV power plants and their benefits

• " Different configurations of solar PV systems, such as grid-connected, stand-alone, and hybrid solar PV plants

• " Metering mechanisms, such as net metring and gross metring

• " Working and classification of different types of inverters used in solar energy generation

• " Different performance evaluation parameters for solar PV power plants and effect of environmental conditions

• " Components used in solar PV power plants

• " Challenges related to the large-scale integration of solar PV plants with the power grid

Introduction

Solar energy is a renewable source of energy, and when electricity is produced from solar, it does not lead to any CO2 emissions. Apart from being a green and renewable source of energy, solar is the simplest system of electricity generation. As described by Professor Martin Green, ‘The whole photovoltaic technology itself is a bit magical. Sunlight just falls on this inert material and you get electricity straight out of it.’ This technology has emerged as the most powerful solution for decarbonizing the energy system.

The solar PV plants can be installed in two modes: grid-connected and off-grid system. At present, grid-connected solar PV (GCSPV) plants are the most commonly used systems. Although solar PV cells, were discovered in the year 1953, solar PV plants for generating electricity did not gain widespread acceptance primarily because of the panel cost as well as the issues with the batteries involved. GCSPV technology has removed the weak link, the battery from the system, making it an efficient, economical, and durable system with minimum maintenance requirements. These benefits have made the solar PV the fastest rising system in the world.

Introduction

A current mirror is a transistor-based circuit that the current level is controlled in an adjacent transistor, and the adjacent transistor essentially acts as a current source. Such circuits are now considered a commonly used building block in a number of analog integrated circuits (IC). Operational amplifiers, operational transconductance amplifiers, and biasing networks are examples of such circuits that essentially use current mirrors. Analog IC implementation techniques such as current-mode and switched-current circuits use current mirrors as basic circuit elements.

A significant advantage associated with the current mirrors is that they act as a near-ideal current source while fabricated using transistors and can replace large-value passive resistances in analog circuits, saving large chip area.

The later part of the chapter discusses another important analog circuit, namely, differential amplifier. As the name suggests, differential amplifiers amplify the difference between two signals that are applied to their two inputs. In addition to the differential amplification, it is also required that differential amplifiers suppress unwanted signal, which is present on the two input signals in the form of a common-mode signal. A differential amplifier is a particularly very useful and essential part of operational amplifiers. A differential pair is the basic building block of a differential amplifier that comprises of two transistors in a special form of connection.