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 in Common Emitter Amplifier
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Today weβll start with how current mirrors work in common emitter amplifiers. Can someone tell me what a current mirror is?
Isnβt it a circuit that produces a constant output current regardless of the load?
Exactly! In a common emitter amplifier, the current mirror sets the reference current. To recall, the reference current, denoted as I_REF, can be calculated using the equation I_REF = V_Bias/R_Bias. Can anyone explain why using a current mirror is preferable?
It improves output stability and allows for better performance due to matching transistors!
Correct! Matching transistors reduce gain variation. Letβs summarize these key points: 1. A current mirror stabilizes currents. 2. It enhances amplifier performance.
Common Collector Amplifier Functionality
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Now, let's move to the common collector configuration. Who can tell me the main function of this amplifier type?
Itβs primarily used for impedance matching, right?
Good point! Can anyone explain how the current mirror integrates here?
It sets the emitter current for the main transistor!
Exactly! And as we've seen, itβs crucial that the collector current approximates the reference current multiplied by a certain factor. Remember this acronym: IC = I_REF * Ξ². What does Ξ² represent?
It represents the transistor's current gain.
Thatβs right! So, we need to remember the impact of these gain factors in CC amplifiers.
Differential Amplifier Configurations
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Weβve covered CE and CC amplifiers, now let's focus on differential amplifiers. What are some benefits of using a current mirror in this setup?
It can replace the tail resistor and improve common-mode gain!
Exactly! By replacing the tail resistor with an active current mirror, we enhance performance significantly. Can you explain how this affects common mode and differential mode gains?
The tail current mirror stabilizes the reference current, thus improving differential mode gain while reducing common mode gain.
Well summarized! Remember as an easy mnemonic to keep in mind: CC = CMoG + DMg, where CC symbolizes Current Control, CMoG is Common Mode Gain, and DMg is Differential Mode Gain.
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
The section elaborates on how current mirrors can set reference currents in various amplifier configurations, such as common emitter (CE), common collector (CC), and differential amplifiers, highlighting their significance and operational mechanisms.
Detailed
Analog Electronic Circuits - Usage of Current Mirrors
This section focuses on the implementation and advantages of using current mirrors in various amplifier settings, particularly in common emitter, common collector, and differential amplifiers. Current mirrors are essential for establishing stable reference currents that enhance amplifier performance. In a common emitter configuration, for instance, a current mirror can manage the collector current output effectively, assuming ideal conditions such as transistor matching. Similarly, in common collector and differential amplifier configurations, well-constructed current mirrors improve gain and stability through active load balancing. The section outlines key equations and analyses necessary for assessing gain and operating points in these configurations, emphasizing the role of reference currents and the importance of ideal conditions in practical applications.
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
So, dear students welcome back after the break. So, before the break we are talking about usage of current mirror for CE amplifier, and also CS amplifier. Now we also can see that usage of current mirror for Common Collector amplifier as well.
Detailed Explanation
In this chunk, we return to the topic of current mirrors in amplifiers. After discussing their use in CE (Common Emitter) and CS (Common Source) amplifiers, we will expand our focus to the Common Collector amplifier. This indicates a variety of applications for current mirrors across different amplifier configurations, emphasizing their versatility in analog electronic circuits.
Examples & Analogies
Think of current mirrors as a method of distributing power in a network. Just like water can be divided into two pipes of different widths to provide flow to various parts of a garden, current mirrors help in managing the flow of electrical current to support different amplifier setups.
Circuit Overview
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, here we do have the transistor level circuit transistor-1 it is the main amplifying transistor input port is here. And then the output port it is here and earlier what we said is that the current of this transistor it can be set by one reference current.
Detailed Explanation
In this section, we discuss the layout of the circuit focusing on transistor-1, which serves as the main amplifying component. The input and output ports are identified here, and the significance of a reference current is introduced. This reference current is crucial because it determines the operation of the amplifying transistor, allowing for stable and predictable function.
Examples & Analogies
Imagine a chef preparing a recipe. The reference current is like a key ingredient that ensures the dish tastes right. Without the correct amount of that ingredient, the final dish could vary widely, just as the transistor's current would deviate without an appropriate reference.
Importance of the Bias Resistor
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, we do have this R and based on the value of this R we can get a current here and we call this is I the reference current.
Detailed Explanation
The bias resistor R plays a critical role in setting the reference current I for the transistor. By adjusting the value of R, we can control how much current flows through the transistor, which is vital for maintaining optimal performance in the circuit. This relationship highlights the importance of resistor selection in circuit design.
Examples & Analogies
You can think of the bias resistor as the throttle in a car. Just as the throttle controls the amount of fuel that flows to the engine, thus controlling the speed of the car, the resistor controls the current to the transistor, ensuring it operates effectively.
Equations for Collector Current
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, this is the exact equation assuming transistor-2 and transistor-3 they are identical and then this may be well approximated by Γ IREF.
Detailed Explanation
Here we derive an equation for the collector current of transistor-2 based on the assumption that it is identical to transistor-3. This approximation allows for simplification in calculations, which is a fundamental concept in circuit analysis. Understanding how to manipulate and utilize these equations is key for diagnosing and optimizing amplifier performance.
Examples & Analogies
This is akin to simplifying complex math problems: if two variables are equal, we can treat them as one, reducing computation time and effort. This makes it easier for engineers to design and troubleshoot circuits.
Common Collector Amplifier and Current Mirrors
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, similar to common collector amplifier the current mirror can also be used for common drain amplifier which is the MOSFET counterpart of this circuit.
Detailed Explanation
In this chunk, the applicability of current mirrors extends to common drain amplifiers (the MOSFET equivalent of common collector amplifiers). This connection further showcases how current mirrors are essential across various transistor technologies in constructing reliable and effective amplifiers.
Examples & Analogies
Imagine using the same recipe book (current mirror) for two different types of meals (amplifiers); although the meals may require slight adjustments, the fundamental method is the same. This highlights how versatile the current mirror approach is within different amplifier contexts.
Application in Differential Amplifiers
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, of course, since both the resistors are very high you can well approximate this by 1. Now, next thing is that the current mirror can also be used our rather frequently used for differential amplifier.
Detailed Explanation
This section transitions to exploring the use of current mirrors in differential amplifiers, setting the stage for discussing how they can enhance circuit performance. The approximation of high resistors simplifies analysis, enabling clearer focus on the advantages brought by current mirrors in this context.
Examples & Analogies
Imagine enhancing a sports team by bringing in versatile players who can adjust to different positions based on the game needs. Current mirrors make differential amplifiers more adaptable, allowing for improved performance across varying scenarios.
Tail Current and Common Mode Gain
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
In fact, there are different possible applications and the applications of the current mirror on differential amplifier it is having 3 folds.
Detailed Explanation
In this section, we discuss the multiple benefits that current mirrors bring to differential amplifiers, one of which includes enhancing the common mode gain. This concept is critical as it directly links to the amplifier's ability to reject noise anddistortions, showcasing the practical superiority of their implementation.
Examples & Analogies
Think of a noisy room. A good discussion group (differential amplifier) should drown out the noise (common mode signals). By using current mirrors (filters), the group can focus more effectively on their conversation, reducing the impact of the disturbances around them.
Replacing Passive Loads
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, now if you replace the load part by active current mirror then what will be getting is the improvement of common mode and differential mode gain.
Detailed Explanation
This segment highlights how replacing passive loads with active devices, such as current mirrors, results in enhanced performance of differential amplifiers. This transformation can dramatically improve both the common mode and differential mode gains, leading to a better overall circuit performance.
Examples & Analogies
This is akin to upgrading from manual gears to automatic gears in a vehicle; the car (differential amplifier) becomes more efficient and responsive to changes (gains), elevating the overall driving experience.
Conclusion on Differential Amplifier Performance
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, we do obtain the current here in terms of I. Likewise, here also we can get the current relationship namely Iβ² it becomes I Γ by dropping ( ) part.
Detailed Explanation
In the final chunks, we summarize the current relationships established through previous equations. Understanding these relationships forms a basis for evaluating how modifications to the transistor arrangement can improve circuit operations. This level of comprehension allows engineers to make informed design choices.
Examples & Analogies
Consider a weaving pattern in a fabric. Each thread (current) needs to connect properly to create a cohesive fabric (circuit). By understanding and manipulating these intersections, we can create stronger and more complex structures, much like engineered circuits.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
-
Current Mirror: A circuit configuration that mimics the current flowing through one active device by controlling it with another.
-
Reference Current: The fixed current used to set the operating point of an amplifier and ensure more predictable performance.
-
Common Collector Configuration: A method of amplifier design focusing on buffering and low output impedance.
-
Differential Mode Gain: The amplification factor for the difference between two input signals in a differential amplifier.
-
Common Mode Gain: The amplification factor for signals that are common to both inputs in a differential amplifier.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
-
In a common emitter amplifier, a current mirror can adjust the reference current to maintain a steady output voltage during broadband signals.
-
A differential amplifier using current mirrors effectively suppresses common mode interference due to better load balancing.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
π΅ Rhymes Time
-
Mirror, mirror in the circuit, reflecting current without a limit.
π Fascinating Stories
-
Imagine a reflection pool where every time you drop a pebble, the ripple on the surface reflects that energy. This is akin to the current mirror, ensuring that no matter the load, the effect is mirrored back consistently.
π§ Other Memory Gems
-
Use 'CORRECT' to remember: C for Current, O for Output, R for Reflection, R for Resistor (in Bias), E for Emitter, C for Collector, T for Tail (in Differential).
π― Super Acronyms
MEMORIZE
- M: for Matching
- E: for Efficiency
- M: for Maintaining
- O: for Output
- R: for Reference
- I: for Impedance
- Z: for Zeal (enthusiasm for understanding).
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
-
Term: Current Mirror
Definition:
A circuit that produces an output current proportional to an input reference current.
-
Term: Reference Current (I_REF)
Definition:
A stable current used in various amplifier configurations, set by a bias voltage and resistor.
-
Term: Common Emitter Amplifier (CE)
Definition:
An amplifier configuration known for high gain and good input-output relation.
-
Term: Common Collector Amplifier (CC)
Definition:
An amplifier configuration that allows for impedance matching and produces a voltage similar to its input.
-
Term: Differential Amplifier
Definition:
An amplifier that amplifies the difference between two input signals.