Overview
This first lecture introduces the basics of analog circuits, key differences between analog and digital systems, amplifiers, and an outline of the course content.
Introduction to Analog Circuits
- Analog circuits handle continuous signals found in the real world, such as sound and temperature.
- Most natural phenomena and sensor outputs are analog, although computers process digital signals.
- Analog-to-digital converters (ADCs) are required to make analog signals usable for digital systems.
Analog vs Digital Signals
- Analog signals are continuous, while digital signals are discrete.
- Example: Mercury thermometers (analog) show continuous temperature values; digital thermometers display values at set increments.
- Digital systems cannot represent values between measured steps, while analog systems can.
Amplifiers and Their Importance
- Amplifiers convert weak signals into stronger signals for easier processing and transmission.
- Sensor outputs are often very small and need amplification to avoid being corrupted by noise.
- Amplifiers help maintain signal integrity by boosting signal power and minimizing the effect of noise.
Amplifier Functionality and Types
- Amplifiers increase signal power, not just voltage or current.
- Transformers can step up voltage or current but do not amplify power; only amplifiers do.
- Power for amplification comes from both the input signal and a DC supply (battery).
Circuit Elements: Active, Passive, Linear, Non-Linear
- Active elements (like transistors) amplify signals; passive elements (resistors, capacitors, inductors) do not.
- Linear elements respond proportionally (e.g., resistors), while non-linear elements do not (e.g., diodes, transistors).
Discrete Circuits vs Integrated Circuits (ICs)
- Discrete circuits are built using separate components on breadboards or PCBs, common in labs.
- Integrated circuits (ICs) combine components onto a single chip, saving space, power, and increasing reliability.
- Analog circuit study usually focuses on discrete circuits due to accessibility.
Course Structure Preview
- Unit 1: Diode circuits, transistors, biasing, small signal analysis, amplifier configurations (BJT and MOSFET).
- Unit 2: Frequency response of amplifiers, feedback, and stability.
- Unit 3: Oscillators, use of positive and negative feedback.
- Unit 4: Current mirrors, differential amplifiers.
- Unit 5: Operational amplifiers (op-amps), their applications, and active filter design.
Key Terms & Definitions
- Analog Signal — A continuous signal that varies smoothly over time.
- Digital Signal — A signal that has discrete levels or steps.
- Amplifier — A circuit that increases the power of a signal.
- Active Element — A component that can amplify a signal (e.g., transistor, op-amp).
- Passive Element — A component that cannot amplify (e.g., resistor, capacitor, inductor).
- Op-Amp (Operational Amplifier) — A high-gain voltage amplifier with various applications.
- Active Filter — A filter circuit using op-amps and passive elements.
Action Items / Next Steps
- Prepare for the next class on diode circuits.
- Review basic concepts of analog and digital signals, amplifier functions, and circuit elements.