What should I focus on for WJEC-CBAC A-Level Design and Technology?

Always draw the I-V characteristic with voltage on the horizontal axis and current on the vertical; label the forward threshold voltage clearly.

What should I focus on for WJEC-CBAC A-Level Design and Technology? (2)

In rectifier circuit analysis, check diode orientation carefully and explain how it determines conduction during positive or negative half-cycles.

What should I focus on for WJEC-CBAC A-Level Design and Technology? (3)

When describing clipping circuits, use precise terms such as 'positive peak clipped' or 'voltage limiter' and include supporting waveform sketches.

What should I focus on for WJEC-CBAC A-Level Design and Technology? (4)

Memorise typical values: 0.7 V forward drop for silicon, and remember that reverse leakage current is typically in the nanoamp range.

What should I focus on for WJEC-CBAC A-Level Design and Technology? (5)

Always label axes, key voltages, and current directions when drawing I-V characteristic graphs

What are common mistakes in WJEC-CBAC A-Level Design and Technology?

Confusing the roles of forward and reverse bias, leading to incorrect diode orientation in circuit diagrams.

What are common mistakes in WJEC-CBAC A-Level Design and Technology? (2)

Misinterpreting the I-V characteristic by assuming linear behaviour or neglecting the knee region.

What are common mistakes in WJEC-CBAC A-Level Design and Technology? (3)

Overlooking the 0.7 V forward voltage drop when calculating rectifier output voltages.

Design and Technology

WJEC-CBAC

A-Level

Specification: 603/0777/8

This subject will help you develop key knowledge and skills required for exam success.

Topics

Objectives

Exam Tips

Pitfalls

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Key Features

Master key concepts
Develop exam technique
Apply knowledge effectively

Assessment Objectives

AO1

13%-15%

Identify, investigate and outline design possibilities to address needs and wants

AO2

23%-25%

Design and make prototypes that are fit for purpose

AO3

23%-25%

Analyse and evaluate: • design decisions and outcomes, including for prototypes made by themselves and others • wider issues in design and technology

AO4

38%-40%

Demonstrate and apply knowledge and understanding of: • technical principles • design and making principles

What Gets Top Grades

A*/Grade 9

Knowledge & Understanding

Demonstrates comprehensive and accurate knowledge

Uses correct subject-specific terminology
Shows detailed understanding of concepts
Makes accurate connections between topics
Demonstrates depth beyond surface-level knowledge

Application

Applies knowledge effectively to new contexts

Selects relevant knowledge for the question
Adapts understanding to unfamiliar scenarios
Uses examples appropriately
Shows awareness of context

Analysis & Evaluation

Develops sophisticated analytical arguments

Constructs logical chains of reasoning
Considers multiple perspectives
Weighs evidence to reach justified conclusions
Acknowledges limitations and nuances

Key Command Words

WJEC-CBAC

State

1 mark

Give a single fact or term

Identify

1 mark

Name, select, or recognise

Outline

2 marks

Set out main features briefly

Describe

2-4 marks

Give an account of what something is like or what happens

Explain

3-6 marks

Give reasons with developed cause→effect chains

Compare

2-4 marks

State similarities AND differences (both required)

Analyse

6-9 marks

Examine in detail showing cause→effect→consequence chains

Evaluate

6-12 marks

Weigh up BOTH sides, reach JUSTIFIED conclusion

Assess

6-12 marks

Make judgments about importance with justification

Calculate

2-4 marks

Show formula→substitution→calculation→answer with units

Common Exam Mistakes

Pitfalls to avoid in your exams

•Confusing the roles of forward and reverse bias, leading to incorrect diode orientation in circuit diagrams.
•Misinterpreting the I-V characteristic by assuming linear behaviour or neglecting the knee region.
•Overlooking the 0.7 V forward voltage drop when calculating rectifier output voltages.
•Failing to distinguish between half-wave and full-wave rectifier output waveforms and ripple frequencies.
•Applying clipping circuits without considering the effect of the diode's forward voltage on clipping threshold.
•Confusing conventional current direction with electron flow in forward and reverse bias
•Incorrectly assuming the depletion region completely disappears under forward bias
•Misidentifying the polarity of the barrier potential relative to the applied voltage

Top Examiner Tips

Expert advice for exam success

•Always draw the I-V characteristic with voltage on the horizontal axis and current on the vertical; label the forward threshold voltage clearly.
•In rectifier circuit analysis, check diode orientation carefully and explain how it determines conduction during positive or negative half-cycles.
•When describing clipping circuits, use precise terms such as 'positive peak clipped' or 'voltage limiter' and include supporting waveform sketches.
•Memorise typical values: 0.7 V forward drop for silicon, and remember that reverse leakage current is typically in the nanoamp range.
•Always label axes, key voltages, and current directions when drawing I-V characteristic graphs
•Use precise technical terms: 'depletion region', 'barrier potential', 'majority carriers', and 'space charge'
•Relate explanation to device behaviour: link forward bias to low resistance and reverse bias to high resistance
•Practise sketching band diagrams to visually demonstrate depletion region and potential barrier changes under bias

Specification Topics

7 topics

Semiconductors and Diodes

This subtopic covers the fundamental electrical behaviour of silicon diodes, focusing on their current-voltage (I-V) characteristic and its practical applications in shaping and converting signals. Students will learn to interpret the diode's forward and reverse bias regions, understand key parameters such as threshold voltage, and apply this knowledge to analyse rectification (AC to DC conversion) and clipping circuits used in electronic systems.

Diode Characteristics and Applications, The p-n Junction, Semiconductor Materials

0 objectives13 tips14 pitfalls3 subtopics

Transistors and Amplifiers

This subtopic delves into the foundational semiconductor device, the Bipolar Junction Transistor (BJT), focusing on its physical construction, biasing requirements, and operational principles as a current amplifier. Learners explore how npn and pnp types differ in carrier flow and terminal voltages, and critically, how the current gain (β) quantifies the transistor's amplification capability, a parameter essential for biasing calculations and circuit design within analogue electronic systems.

Bipolar Junction Transistors (BJT), Common Emitter Amplifier, Field Effect Transistors (FET)

0 objectives13 tips13 pitfalls3 subtopics

Operational Amplifiers

This subtopic examines the defining characteristics of an ideal operational amplifier, such as infinite gain and input impedance, and introduces the virtual earth concept crucial for circuit analysis. These foundations underpin the design of linear amplifiers, filters, and comparators, enabling precise signal processing in real-world electronic systems. Mastery of op-amp characteristics is vital for tackling complex circuits in design and technology applications, from sensor interfacing to active filter design.

Op-Amp Characteristics, Inverting and Non-Inverting Amplifiers, Op-Amp Applications

0 objectives11 tips12 pitfalls3 subtopics

Digital Electronics

This subtopic covers the fundamental building blocks of digital systems: logic gates such as AND, OR, NOT, NAND, NOR, XOR, and XNOR. Learners develop the ability to draw standardised symbols and use Boolean algebra to describe and simplify logic functions, applying laws like commutativity, distributivity, and De Morgan's theorem. Mastery of these concepts enables efficient digital circuit design and troubleshooting in practical contexts like microcontroller programming and electronic product development.

Logic Gates and Boolean Algebra, Combinational Logic Circuits, Sequential Logic Circuits

0 objectives11 tips12 pitfalls3 subtopics

Timing Circuits

This subtopic explores the transient behaviour of resistor-capacitor (RC) circuits, focusing on how capacitors charge and discharge through resistors. It covers the mathematical modelling of exponential voltage and current changes, the significance of the time constant (τ = RC), and practical applications in timing, filtering, and waveform generation. Understanding these principles is essential for designing reliable timing circuits in electronic products.

RC Timing Circuits, 555 Timer

0 objectives10 tips10 pitfalls2 subtopics

Power Supplies

This subtopic explores the conversion of alternating current (AC) to direct current (DC) through rectification and the subsequent reduction of output voltage fluctuations using smoothing capacitors. Understanding these processes is essential for designing stable, low-ripple power supplies for electronic circuits, ensuring reliable operation of components such as amplifiers, microcontrollers, and logic devices.

Rectification and Smoothing, Voltage Regulation

0 objectives10 tips11 pitfalls2 subtopics

Measurement and Testing

This subtopic covers the practical application of signal generators to produce various waveforms for testing and the measurement of frequency response in amplifiers, essential for evaluating electronic circuit performance and ensuring design specifications are met.

Signal Generators and Frequency Response, Oscilloscope and Multimeter

0 objectives8 tips8 pitfalls2 subtopics

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