Homeschool Guide: These lesson plans are a guide for parents. Content may contain errors — always cross-reference with official exam board specifications.

amplifier circuits

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4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.

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Lesson Overview

Total Lessons: 4
Tier: Foundation and Higher
Duration: 50 minutes per lesson (200 minutes total)
Exam Boards: AQA, Edexcel, OCR, Eduqas, CCEA

Learning Objectives

Prerequisites

Materials & Equipment

Lesson 1: Introduction: amplifier circuits

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Write down everything you already know about amplifier circuits. Then check against the key terms: key terms from amplifier circuits. Use a mini-whiteboard or paper.

Main Content (35 minutes)

Parent/Teacher Guide:
Before lesson: Read the script below. Pre-teach key vocab: key terms from amplifier circuits.
If stuck: Re-read the revision notes (link above), then break the content into smaller steps.
Extension: See the Stretch & Challenge ideas in Lesson 4.
Teaching Script (35 mins):
Mins 0-5 - Hook: "Today: amplifier circuits. By the end you will be able to answer exam questions on it unaided. It connects to the rest of Electronics because the ideas here recur across the spec."
Mins 5-20 - Direct Instruction: Work through the core ideas below one at a time; after each, ask your student to explain it back in their own words.
Mins 20-30 - Guided Practice: Model the worked example together, then let your student attempt the first practice question with guidance.
Mins 30-35 - Independent Practice: 2-3 practice questions from Lesson 3 below, with immediate feedback.
First Look

Start with the revision notes summary, then attempt: explain the key ideas of amplifier circuits

Plenary (5 minutes)

Check Out

Your student states one thing they learned and one question they still have about amplifier circuits.

Lesson 2: Core Concepts: amplifier circuits

Duration: 50 minutes

Starter Activity (5 minutes)

Review Previous Lesson

Quick recap: write 3 key points from Lesson 1 on amplifier circuits. Check them against the notes below.

Main Content (35 minutes)

Key Fact: Voltage gain is the ratio of output voltage to input voltage: Av = Vout/Vin; it can be expressed as a number or in decibels (dB).
Key Fact: Gain in decibels: G(dB) = 20 log₁₀(Av); a gain of 10 equals 20 dB, a gain of 100 equals 40 dB.
Key Fact: Bandwidth is the range of frequencies over which the amplifier operates within specification, typically defined between the −3 dB points.
Key Fact: The gain-bandwidth product (GBW) is constant for a given op-amp: as closed-loop gain increases, bandwidth decreases proportionally.
Key Fact: Negative feedback reduces gain but increases bandwidth, improves linearity and stabilises the circuit against component variations.
Key Fact: The inverting amplifier has Av = −Rf/Rin; its input impedance equals Rin (not the op-amp's input impedance).

Practice (10 minutes)

Q: explain the key ideas of amplifier circuits

Answer:

Plenary (5 minutes)

Explain Back

Your student teaches the key points back to you without looking. Fill any gaps immediately.

Lesson 3: Application: amplifier circuits

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Recall the key terms: key terms from amplifier circuits. Define each in one sentence.

Main Content (35 minutes)

Parent/Teacher Guide: Let your student attempt each question alone first, then compare with the model answer. Award method marks for correct working even if the final answer is wrong.

Work through the practice questions on the revision notes page for this topic.

Plenary (5 minutes)

Error Review

Review any questions answered incorrectly. Identify whether the error was knowledge, method, or reading the question.

Lesson 4: Exam Practice: amplifier circuits

Duration: 50 minutes

Starter Activity (5 minutes)

Command Words

Review what these command words require: state (one point), describe (say what happens), explain (say why), compare (both sides), evaluate (judgement).

Main Content (35 minutes)

Extended Answer

Extended question: Full-Mark Response Explain the concept of gain-bandwidth product and describe how a summing amplifier combines multiple input signals. <div class="

The gain-bandwidth product (GBW) is a constant for a given op-amp, representing the frequency at which the open-loop gain falls to unity (0 dB). For any closed-loop configuration, the product of gain and bandwidth equals the GBW: as closed-loop gain increases, bandwidth decreases proportionally. For example, a 741 op-amp with GBW = 1 MHz has a bandwidth of 1 MHz at unity gain, 100 kHz at Av = 10, and 10 kHz at Av = 100. A summing amplifier is an inverting op-amp circuit with multiple input resistors connected to the inverting input. Each input voltage is weighted by the ratio Rf/Ri, and the output is the inverted sum: Vout = −Rf(V1/R1 + V2/R2 + … + Vn/Rn). When all input resistors are equal (Ri = R), the output is simply −(Rf/R)(V1 + V2 + … + Vn), making it a true analogue adder. This circuit is used in audio mixing, DACs and analogue computation.

Exam Tips: Convert between linear gain and dB: G(dB) = 20 log₁₀(Av); Av = 10^(G/20). | For summing amplifier questions, write the full equation first, then substitute values step by step. | Remember the output of a summing amplifier is inverted — include the minus sign. | When discussing bandwidth, always refer to the −3 dB point as the definition of bandwidth. | Use the gain-bandwidth product to find bandwidth: BW = GBW/closed-loop gain.
Common Errors: ✗ Using power gain formula (10 log₁₀) for voltage gain in dB. ✓ Voltage gain in dB uses 20 log₁₀(Av); power gain uses 10 log₁₀(Pout/Pin). ✗ Assuming the input impedance of an inverting amplifier equals the op-amp's input impedance. ✓ The input impedance of an inverting amplifier equals Rin, because the inverting input is a virtual earth. ✗ Forgetting that a summing amplifier's output is inverted. ✓ The output of a summing amplifier is negative (inverted); Vout = −Rf(Σ Vi/Ri). ✗ Confusing open-loop bandwidth with closed-loop bandwidth. ✓ Open-loop bandwidth is very small (a few Hz); closed-loop bandwidth = GBW/closed-loop gain.
Stretch & Challenge (Grade 8-9):
  • Synoptic links: explain how amplifier circuits connects to another Electronics topic you have studied
  • Real-world: research one real-world use or example of amplifier circuits
  • Critical: "What are the limitations of the models used in amplifier circuits?"

Plenary (5 minutes)

Assessment Criteria
  • Got it: Confident explanation + correct worked examples
  • Getting there: Main points OK, needs support with detail
  • Not yet: Confused on key concepts - re-run Lesson 2

Homework & Consolidation

Recommended Resources

🎓 Smart Lesson (Guided)