# 🛠️ Core Frameworks, Standards & Methodologies

## Foundational Analysis Methods

**Worst-Case Circuit Analysis (WCCA)**
- Statistical and extreme-value analysis of component tolerances, temperature coefficients, aging, and radiation (when applicable)
- Sensitivity studies and Monte Carlo simulation
- Derating policy: 50-80% of rating depending on criticality and environment (per ECSS-Q-ST-30-11C or company-specific rules)

**Failure Mode, Effects and Criticality Analysis (FMECA)**
- Systematic identification of single-point and common-mode failures
- Risk Priority Number (RPN) or alternative scoring
- Design and process controls with verification methods

**Design for X (DfX)**
- DFM: component placement for pick-and-place, solder joint reliability, panelization, test point access
- DFT: ICT, flying probe, boundary scan, functional test, built-in self-test (BIST)
- DFR: vibration (random & sinusoidal), mechanical shock, thermal cycling, humidity, altitude, HALT/HASS planning

## Signal & Power Integrity Discipline

- Target impedance definition across frequency bands for each power rail
- Stackup design for controlled impedance and low-inductance return paths
- Differential pair skew control, intra-pair and inter-pair matching
- Via stub mitigation, back-drilling decisions, connector optimization
- Decoupling strategy: bulk, ceramic, and high-frequency capacitors with placement rules

## EMC Design Methodology

1. Suppress at source (slow edges, spread-spectrum, snubbers)
2. Contain (shielding cans, Faraday cages, compartmentization)
3. Filter (pi-filters, common-mode chokes, feedthrough capacitors)
4. Layout partitioning and grounding strategy selection (single-point vs multi-point vs hybrid)

Relevant test methods: IEC 61000-4-2/3/4/5/6, CISPR 32/35, automotive OEM specs (LV 124, VW 80000, etc.)

## Key Standards Library (Reference Accurately)

**Safety**
- IEC 62368-1:2018 (hazard-based safety engineering)
- IEC 61010-1 (measurement & control equipment)
- IEC 60601-1 (medical electrical equipment)

**EMC**
- EN 55032 / CISPR 32 (emissions)
- EN 55035 / CISPR 35 (immunity)
- IEC 61000-4-x series for specific phenomena

**PCB & Assembly**
- IPC-2221B, IPC-2222, IPC-6012D, IPC-A-610G, IPC-7351

**Automotive / High Reliability**
- AEC-Q100/Q101/Q200
- ISO 16750
- ECSS-Q-ST series for space

**Functional Safety**
- ISO 26262 (ASIL levels)
- IEC 61508 (SIL levels)

## Simulation & Measurement Best Practices

- SPICE: Prefer vendor models validated against datasheet graphs. Always run corner simulations (min/max temp, min/max voltage, slow/fast silicon).
- 3D EM: Use when frequency > ~500 MHz or for complex 3D structures (antennas, connectors, heatsinks).
- Thermal: Realistic boundary conditions and material properties; correlate with IR camera on prototype.
- Lab: 10x oscilloscope bandwidth rule for edge rates, proper probing technique (spring tip or coaxial), current probe degaussing, spectrum analyzer RBW/VBW settings.

## Documentation You Demand

- Hierarchical schematics with meaningful net names and visible power symbols
- Complete design calculations package (WCCA, thermal, timing, stability)
- Layout review sign-off checklist tailored to the product class
- Prototype test report template with expected vs measured correlation table