Professional Courses
Industry-relevant training in Business, Technology, and Design to help professionals and graduates upskill for real-world careers.
Categories
Interactive Games
Fun, engaging games to boost memory, math fluency, typing speed, and English skillsβperfect for learners of all ages.
Typing
Memory
Math
English Adventures
Knowledge
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Current Mirror Basics
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Welcome back, everyone! Today, we're going to learn about a crucial element in analog circuits known as the current mirror. Does anyone know what a current mirror does?
I think it helps replicate current from one part of the circuit to another?
Exactly! A current mirror replicates the current flowing through a reference branch to another output branch. Think of it as a 'mirror' reflecting the flow of current.
Why is that important in circuits?
Great question! It's essential for ensuring stable and predictable performance in circuits like amplifiers, where consistent bias currents are crucial for functionality.
Can we see how it works through examples?
Of course! We'll explore several applications in common amplifier configurations later in our session. Remember, CRISP stands for Current Replication in Signal Processing!
That's a good way to remember it!
Now let's proceed to its applications.
Applications of Current Mirrors
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Let's talk about where current mirrors are used. One example is in common emitter amplifiers. Can anyone describe what a common emitter amplifier is?
It's a circuit configuration where the input is applied to the base, and the output is taken from the collector.
Correct! Now, in a common emitter configuration, how do you think a current mirror can improve performance?
It could help set up a more stable bias current?
Yes, thatβs right! It ensures that the transistors operate efficiently in their active region. We'll now illustrate a simplified diagram of a common emitter amplifier using a current mirror.
Can we also talk about differential amplifiers?
Absolutely! Current mirrors are also used for biasing in differential amplifiers, which weβll discuss in our next session. Remember, it's crucial for maintaining matching and stability in differential configurations.
This really connects to all the principles weβve learned before!
Small Signal Models
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Now, letβs explore the small signal model for current mirrors. This is essential for analyzing how the circuit behaves with AC signals. What do you think happens in DC conditions?
The circuit would open, right?
Exactly! In a DC condition, the small signal equivalent circuit simplifies to an open circuit. What about when signal currents are present?
We have to consider both the DC and AC components?
Yes! The current mirror will not behave the same and requires a modified small signal model to analyze its performance. Remember, OUTLOOK stands for Open Under Test, Linear Outcomes with Current mirrors!
Thatβs helpful. Can we practice how to draw the small signal circuit next?
Absolutely! We'll practice that right now. Understanding these models will help when simulating circuits later.
I feel more comfortable with this topic after our discussion.
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
The section provides an overview of the current mirror circuit, explaining its operating principles and various applications, particularly in different types of amplifiers such as common emitter, common source, and differential amplifiers. The discussion also includes insights into small signal models and analysis for BJTs and MOSFETs.
Detailed
Usage of Current Mirror in Analog Electronic Circuits
In this section, we delve into the usage of current mirrors, a fundamental concept in analog electronic circuits, particularly in amplifiers.
Key Points Covered:
- Current Mirror Basics: A current mirror is an active device that replicates a reference current through another branch of the circuit. It is pivotal in maintaining consistent current levels in various configurations.
- Applications: The lecture discusses how current mirrors are utilized in various amplifier configurations:
- Common Emitter & Common Source Amplifiers: Current mirrors help in setting bias points and ensure that the transistors operate in the desired region.
- Common Collector & Common Drain Configurations: They provide high input resistance and low output resistance.
- Differential Amplifiers: Serve as a biasing element and contribute to signal strength and integrity.
- Small Signal Model: The small signal model for the current mirror is pivotal for analyzing circuit behaviors:
- In DC Condition: The circuit appears open for AC signals, making it simpler for analysis.
- With Signal Current: The current mirror changes its behavior and requires an adjusted model to account for the input AC signals.
The detailed discussions provide insights into using the current mirror in practical circuits with a focus on how to derive smaller equivalent circuits for analysis, illustrating both BJT and MOSFET scenarios. This knowledge is essential for students pursuing electronics and electrical engineering, particularly in understanding analog circuit design.
Youtube Videos
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Introduction to Current Mirrors
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Dear students welcome back to our online certification course on Analog Electronic Circuits, myself, Pradip Mandal from E and EC department of IIT Kharagpur. Todayβs topic of discussion is Usage of Current Mirror. So, we have started the current mirror circuit and today we will be talking about its application.
Detailed Explanation
In this introduction, Professor Pradip Mandal welcomes students back to the course. He emphasizes the focus for the day, which is the application of current mirrorsβa fundamental component in analog electronic circuits. Understanding how current mirrors work and their applications is crucial for students to enhance their knowledge in electronics.
Examples & Analogies
Think of a current mirror like a photocopy machine that can produce duplicates of the same document. Just as a photocopier takes one original document and creates many copies, a current mirror takes an original current and produces an identical current in another part of the circuit.
Overview of Current Mirror Applications
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Today we are going to discuss more detail of the current mirror specifically its application and we do have different applications for this current mirror. One is in common emitter and common source amplifier based on whether it is BJT or MOSFET based implementation.
Detailed Explanation
In this chunk, Professor Mandal highlights various applications of current mirrors in amplifiers such as common emitter and common source configurations. The implication is that these configurations can either use Bipolar Junction Transistors (BJT) or Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFET), illustrating the versatility of current mirrors. This versatility enables engineers to implement current mirrors in diverse scenarios where maintaining consistent current is critical.
Examples & Analogies
Imagine a traffic light system that manages traffic flow in different lanes. Depending on whether you are driving a bicycle (common emitter) or a car (common source), the traffic lights adjust to ensure smooth transitions. Similarly, current mirrors adapt to various types of transistors to ensure optimal current regulation.
Small Signal Model Introduction
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
To understand or to appreciate the effect of common current mirror in amplifier standard amplifier where, we normally talk about the linearized circuit whether it is common emitter or common source or common collector or common drain or for that matter even for differential amplifier.
Detailed Explanation
Professor Mandal introduces the small signal model, emphasizing its importance in analyzing how common current mirrors function within various amplifier configurations. The small signal model allows for simplification during calculations, which aids in determining the behavior of the circuit under small perturbations (or variations). This is a critical step in designing efficient amplifiers that utilize current mirrors.
Examples & Analogies
Consider tuning a musical instrument like a guitar. Initially, the guitar is out of tune, but when you make small adjustments to the tension of each string, it slowly begins to sound just right. Similarly, the small signal model helps engineers make tiny adjustments to the current mirrors, allowing circuits to operate optimally.
DC Condition Small Signal Model
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
We do have two possible situation. One is the current mirror may not be carrying any signal namely under DC condition what is the small signal equivalent circuit.
Detailed Explanation
Here, the discussion shifts to two scenarios regarding the operational state of the current mirror. The first case is when the current mirror does not carry any signal, primarily existing under Direct Current (DC) conditions. In such situations, the small signal equivalent circuit simplifies to an open circuit, which means it does not influence the performance of the main circuit significantly. Understanding this helps in analyzing circuits more easily when no variations occur.
Examples & Analogies
Think of an air conditioner that operates only when the temperature reaches a certain threshold. If the temperature doesnβt change, the air conditioner remains idle and doesnβt impact the overall climate of the room. In similar fashion, when the current mirror operates under DC conditions without signal flow, its effect is negligible.
AC Signal Condition Small Signal Model
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
On the other hand the small signal model for transistor-2 M , we do have g v and v as I said that it is same as v .
Detailed Explanation
This chunk introduces a more complex scenario where the current mirror does carry an alternating current (AC) signal. In this state, the small signal model becomes relevant and analyzes how these signals affect the overall circuit performance. The circuit's response under AC conditions is crucial for various applications as it allows for amplification and processing of small voltage changes.
Examples & Analogies
Imagine a dial on a radio that adjusts the music volume. When the dial is turned slightly, it changes the sound we hear. In electronic circuits, small variations in AC signals affect the output just like slight adjustments in the dial affect music volume.
Current Mirror in Amplifiers
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, let us see that. So, here we do have the current mirror circuit, we do have transistor-1 it is diode connected and the we do have reference current DC current that is getting mirrored into this branch through this transistor-2 and here we do have the application circuit.
Detailed Explanation
Professor Mandal discusses the architecture of the current mirror circuit. In this architecture, a diode-connected transistor is used to establish a reference current that gets replicated in another branch of the circuit. This mirroring effect is pivotal for stabilizing the amplification process in the application circuits, whether those circuits are based on BJTs or MOSFETs. Understanding this configuration is essential in designing circuits that facilitate effective amplification.
Examples & Analogies
Consider a puppet show, where one puppet master controls a string of puppets to make them all move in sync. The master (reference current) gets replicated through the strings (transistors), ensuring that all puppets (current flows) behave similarly and harmoniously.
Practical Applications of Current Mirrors
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, we can say that whatever the current we do have if it is signal current. So, its effect in this application circuit can be considered by considering this voltage dependent current source which is the input signal here multiplied by.
Detailed Explanation
In this concluding discussion, current mirrors' practical applications in circuits handling signal currents are further explored. The circuits need to consider the voltage-dependent characteristics of the current mirrors to analyze how they react to changes in input signals. This understanding allows engineers to optimize their designs for desired outcomes, such as improved gain and efficiency in amplifiers.
Examples & Analogies
Think of a water fountain where the height of the water spout depends on how much water is pushed into it. Similarly, the performance of a current mirror in a circuit depends on the input signal, with the voltage source dictating the 'height' or output current seen at the output.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
-
Current Mirror: A device that replicates current from one branch to another.
-
Common Emitter Amplifier: A configuration where input is applied to the base and output from the collector.
-
Small Signal Analysis: A method to determine how circuits respond to small AC signals around their DC operating points.
-
Differential Amplifier: Amplifies the difference between two signals.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
-
Using current mirrors in the design of a BJT common emitter amplifier to stabilize bias currents.
-
Applying current mirrors in differential amplifiers to enhance signal integrity and reject noise.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
π΅ Rhymes Time
-
A mirror for current, a copy we see, helps our circuits work efficiently!
π Fascinating Stories
-
Imagine a quiet library (current mirror), where every whisper (current) is echoed perfectly to maintain serenity. This is how current mirrors ensure consistent signals in circuits.
π§ Other Memory Gems
-
C.R.I.S.P.: Current Replication In Signal Processing helps remember current mirror applications.
π― Super Acronyms
O.U.T.L.O.O.K.
- Open Under Test
- Linear Outcomes with Current mirrors - a reminder of small signal model functions.
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
-
Term: Current Mirror
Definition:
A circuit configuration that copies a current flowing through one active device into another, maintaining consistency across circuits.
-
Term: Common Emitter Amplifier
Definition:
A type of amplifier configuration in which the emitter terminal of a transistor is connected to a common ground.
-
Term: Small Signal Model
Definition:
A linearized representation of a nonlinear circuit that allows easier analysis of circuit behavior under small deviations from a bias point.
-
Term: Differential Amplifier
Definition:
An electronic amplifier that amplifies the difference between two input signals while rejecting any common signals.