---
title: "Technical dilemmas in circuit design"
subject: "Instrumentation II"
chapter: 7
key: "semester_5/instrumentation_ii:design-dilemmas"
source: https://www.bctengineer.com/q/semester_5/instrumentation_ii/design-dilemmas
site: BCT Engineering
---

# Technical dilemmas in circuit design

Instrumentation II · Chapter 7: Circuit Design

- Asked in: 2074 Asoj, 8 marks
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/instrumentation_ii/design-dilemmas
- Whole chapter: https://www.bctengineer.com/md/semester_5/instrumentation_ii/chapter-7

## Question

During circuit design process, what are some general technical dilemmas faced by engineers? Explain how an engineer can arrive at an optimal solution given the requirements of a customer?

## Short answer

Common dilemmas are speed vs. power, cost vs. performance, accuracy vs. speed, and reliability vs. complexity. An optimal solution is reached by capturing prioritized specs, generating alternatives, evaluating trade-offs with a weighted matrix, prototyping risky areas, and iterating with data-driven negotiation.

## Answer

Circuit design is a set of compromises, because improving one property usually worsens another.

#### Common technical dilemmas
- **Speed vs power:** faster circuits need higher clock/currents, which increases power and heat.
- **Speed vs noise/EMI:** faster edges give better timing but more crosstalk, ringing and radiation.
- **Cost vs performance/quality:** better components and more precision cost more.
- **Accuracy/resolution vs speed:** a high-resolution ADC is slower.
- **Size vs heat and routing:** miniaturised designs have thermal and coupling problems.
- **Reliability vs complexity:** redundancy and features add parts that can themselves fail.
- **Flexibility vs efficiency:** programmable (software) solutions are flexible but slower and costlier in power than dedicated hardware.
- **Time-to-market vs testing,** and **hardware vs software** implementation.
- **Analog vs digital** and **standard vs custom parts** (availability, lifetime support).

#### Reaching an optimal solution
1. **Capture the customer's priorities** and measurable specifications; classify them as must-have, important, and nice-to-have, and agree on the margins.
2. **Generate alternatives** (several architectures/components).
3. **Evaluate trade-offs** by calculation and simulation; use a weighted decision matrix scoring each option against the weighted requirements (cost, power, speed, reliability, size, availability).
4. **Prototype and test** the critical risk areas early.
5. **Optimise iteratively**, relax the less important requirement to meet the key one, and negotiate with the customer using data (e.g. "20 percent more cost gives 2x reliability").
6. **Review and document** the decisions, and keep design margins (derating, tolerance).

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is the speed vs power dilemma?
   A. Faster circuits always use less power
   B. Faster circuits need higher clock/currents, raising power and heat
   C. Power has no relation to speed
   D. Slower circuits get hotter
   Answer: B. Higher speed increases dynamic power and heating. (Key point: Speed vs power)

2. What does faster edge rate cause?
   A. Better timing but more crosstalk, ringing and radiation
   B. Less EMI
   C. Less crosstalk
   D. No change
   Answer: A. Fast edges contain higher-frequency energy. (Key point: Speed vs noise)

3. Which tool helps compare alternatives?
   A. Coin toss
   B. Choosing the cheapest only
   C. Choosing the fastest only
   D. A weighted decision matrix scoring options on weighted requirements
   Answer: D. It quantifies trade-offs against priorities. (Key point: Decision tool)

4. How can an engineer reach the optimal solution?
   A. Satisfy all requirements maximally always
   B. Ignore customer priorities
   C. Classify priorities, evaluate trade-offs, prototype risk areas, relax lesser requirements, document
   D. Skip prototyping
   Answer: C. Iterative trade-offs guided by must-have priorities give the optimum. (Key point: Optimising)

## Related in Instrumentation II

- [Establishing requirements for circuit design](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Areq-to-design) — Instrumentation II, chapter 7, asked 4×
- [General process of creating a PCB](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Apcb-creation-process) — Instrumentation II, chapter 8
- [High speed circuit design guidelines](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Ahigh-speed-guidelines) — Instrumentation II, chapter 7, asked 3×

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