1.4. Analog and Digital Circuits in Systems

Whenever we say types of signals, it is we are assuming signal means it is voltage changing with time. Depending on the emphasis and the allowable levels of the signal, the signal can be different types; namely analog and digital kind of signal.

In contrast to that, in case if we are having a special situation where the signal, it is having distinct levels; may be here also we may say that say V(t), but it may be having say two distinct levels, may be either high or low. By the way it is not mandatory that these two levels it will be expected to be 1 V or 0 V; it may have a range of voltage, which may be accepted as meaningful logic 1.

For instance, we may have a meaningful voltage range, over which we may say that signal it is level 1. So, likewise we may have another acceptable level for 0 levels.

So, if it is within this range we call it is undefined level; for such scenario, since the signal it is having only two levels we call it is binary signals. In case if you are having such kind of distinct levels, need not be only two, but it is having finite levels then we call it is digital signal. These are digital signals, whereas for this case, the signal it can continuously vary in the voltage level voltage scale and this is called analog signal.

In electronics, signals are important because they are used to transmit information. Two main types of signals are discussed: analog and digital signals. An analog signal can take on a continuous range of values and represents information in a way that is similar to the way we perceive it, like sound waves. For example, the volume level of music at any given moment can vary continuously and is thus considered an analog signal.

On the other hand, digital signals have distinct levels, typically represented as high (1) and low (0). These signals are discrete, meaning they can only take specific values within a defined range. For example, in digital electronics, a light switch can either be off (0) or on (1), and there are no levels between these two states. Additionally, digital signals can represent information through combinations of these binary states, allowing for more complex data to be processed efficiently.

Think of analog signals as a dimmer switch for lights, where you can turn the knob to any position to get the desired brightness (analog). In contrast, digital signals are like a standard on/off light switch, where you either flip it to the up position for 'on' or down for 'off' (digital). Just like how a dimmer can create a smooth transition of brightness, analog signals can vary continuously. However, the switch only offers a binary choice: on or off, similar to how digital signals work.

Whenever we are dealing with electronic circuit, it is expected that the circuit the intended circuit should recognize at least one of these kind of signals and based on that we may classify the circuit type also.

So, we may have a scenario where we may have one circuit here, another circuit here and so and so. Each of these circuits may have their own functionalities to perform.

Normally this is referred as analog only, because this signal whatever the signal it is received by this block it is analog in nature. So, without going into any ambiguity, we call this is analog circuit.

Circuits can be classified based on the types of signals they process: analog, digital, or mixed signal. An analog circuit can handle continuous signals that vary smoothly, like temperature or sound levels. On the other hand, a digital circuit processes discrete signals, handling information in binary format, allowing for complex computations with high speed and low power consumption. For instance, while an analog circuit might amplify a sound wave, a digital circuit could be used to store that sound digitally for playback later.

Consider a kitchen blender: when you adjust the speed dial, you are using an analog control to vary the speed continuously (analog). In contrast, a microwave uses set buttons to adjust the power level—each button represents a specific power level (digital). Both circuits serve different types of functionalities based on the nature of the signals they handle.

In the electronic system, we are expecting that there will be a meaningful conversion of a real world signal into the form of electronic signal; likewise, at the output side, there will be a meaningful device which supposed to be converting electrical signal in the form of non-electrical signal.

So, if you see here a typical system, it is mix of an analog circuit and digital circuit. If you see that it looks like within the electronics we do have a digital core, so we can say that this is digital core.

In modern electronic systems, both analog and digital circuits are integrated to interact with the real world effectively. The analog circuitry is essential for converting real-world signals (like sound, light, temperature) into electronic signals. Once these signals are in an electronic form, digital circuits can process them to perform computations, filtering, and more. This integration allows for the blending of real-world data with digital processing power, leading to more advanced technologies such as smartphones and smart home devices.

Imagine a smartphone as an example of an integrated system: the microphone on your phone collects sound (analog signal), and then the analog circuitry converts this sound into an electronic format for the digital processor. The digital processor then analyzes this sound to convert it into text or make a voice call, showcasing how both analog and digital circuits work together to deliver the final product.

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