https://breadpad.com/best-practices/Recent content in Best Practices on BreadpadHugoen-usFri, 10 Jan 2025 00:00:00 +0000https://breadpad.com/best-practices/circuit-design-checklist/Fri, 10 Jan 2025 00:00:00 +0000https://breadpad.com/best-practices/circuit-design-checklist/<h1 id="circuit-design-checklist"> Circuit Design Checklist <a class="anchor" href="#circuit-design-checklist">#</a> </h1> <p>Use this comprehensive checklist before running simulations to catch common errors and ensure reliable results.</p> <h2 id="pre-design-phase"> Pre-Design Phase <a class="anchor" href="#pre-design-phase">#</a> </h2> <h3 id="--requirements-defined"> [ ] Requirements Defined <a class="anchor" href="#--requirements-defined">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Input voltage range specified</li> <li><input disabled="" type="checkbox"> Output voltage/current requirements clear</li> <li><input disabled="" type="checkbox"> Frequency range identified</li> <li><input disabled="" type="checkbox"> Power budget established</li> <li><input disabled="" type="checkbox"> Environmental conditions known (temperature, etc.)</li> <li><input disabled="" type="checkbox"> Performance metrics defined (gain, bandwidth, etc.)</li> </ul> <h3 id="--research-completed"> [ ] Research Completed <a class="anchor" href="#--research-completed">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Similar circuits reviewed</li> <li><input disabled="" type="checkbox"> Component availability checked</li> <li><input disabled="" type="checkbox"> Cost constraints considered</li> <li><input disabled="" type="checkbox"> Design patterns identified</li> <li><input disabled="" type="checkbox"> Potential issues anticipated</li> </ul> <hr> <h2 id="component-placement"> Component Placement <a class="anchor" href="#component-placement">#</a> </h2> <h3 id="--power-supply"> [ ] Power Supply <a class="anchor" href="#--power-supply">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Voltage source(s) placed</li> <li><input disabled="" type="checkbox"> Correct voltage values set</li> <li><input disabled="" type="checkbox"> Ground symbol placed</li> <li><input disabled="" type="checkbox"> Polarity verified</li> <li><input disabled="" type="checkbox"> Source type appropriate (DC/AC/Transient)</li> </ul> <h3 id="--passive-components"> [ ] Passive Components <a class="anchor" href="#--passive-components">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> All resistors placed</li> <li><input disabled="" type="checkbox"> Values use standard series (E12/E24)</li> <li><input disabled="" type="checkbox"> Power ratings considered</li> <li><input disabled="" type="checkbox"> Tolerances noted if critical</li> <li><input disabled="" type="checkbox"> All capacitors placed</li> <li><input disabled="" type="checkbox"> Correct capacitor types (ceramic/electrolytic)</li> <li><input disabled="" type="checkbox"> Voltage ratings exceed circuit voltages</li> <li><input disabled="" type="checkbox"> Polarity correct for electrolytics</li> <li><input disabled="" type="checkbox"> All inductors placed (if any)</li> <li><input disabled="" type="checkbox"> Realistic inductance values</li> </ul> <h3 id="--active-components"> [ ] Active Components <a class="anchor" href="#--active-components">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Semiconductors correctly oriented <ul> <li><input disabled="" type="checkbox"> Diode stripe/cathode marking verified</li> <li><input disabled="" type="checkbox"> BJT pin order: Collector, Base, Emitter</li> <li><input disabled="" type="checkbox"> MOSFET pin order: Drain, Gate, Source</li> </ul> </li> <li><input disabled="" type="checkbox"> Correct component types selected <ul> <li><input disabled="" type="checkbox"> NPN vs PNP for BJT</li> <li><input disabled="" type="checkbox"> N-channel vs P-channel for FET</li> </ul> </li> <li><input disabled="" type="checkbox"> Appropriate models chosen</li> <li><input disabled="" type="checkbox"> Substrate connections verified (MOSFET bulk)</li> </ul> <h3 id="--connections"> [ ] Connections <a class="anchor" href="#--connections">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> All components connected with wires</li> <li><input disabled="" type="checkbox"> No floating nodes</li> <li><input disabled="" type="checkbox"> No unintended shorts</li> <li><input disabled="" type="checkbox"> Wire routing neat and clear</li> <li><input disabled="" type="checkbox"> Critical nodes labeled</li> </ul> <hr> <h2 id="circuit-verification"> Circuit Verification <a class="anchor" href="#circuit-verification">#</a> </h2> <h3 id="--dc-paths"> [ ] DC Paths <a class="anchor" href="#--dc-paths">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Every node has DC path to ground</li> <li><input disabled="" type="checkbox"> No capacitor-only paths in bias networks</li> <li><input disabled="" type="checkbox"> Current source have parallel DC paths</li> <li><input disabled="" type="checkbox"> Floating nodes identified and fixed</li> </ul> <h3 id="--component-values"> [ ] Component Values <a class="anchor" href="#--component-values">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> All values realistic and achievable</li> <li><input disabled="" type="checkbox"> No zero or infinite values</li> <li><input disabled="" type="checkbox"> No extremely small/large values</li> <li><input disabled="" type="checkbox"> Units verified (k vs m vs M)</li> <li><input disabled="" type="checkbox"> Calculated values match placed values</li> <li><input disabled="" type="checkbox"> Hand calculations performed for key parameters</li> </ul> <h3 id="--biasing-for-amplifiers"> [ ] Biasing (for amplifiers) <a class="anchor" href="#--biasing-for-amplifiers">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> DC operating point calculated</li> <li><input disabled="" type="checkbox"> Transistor bias resistors present</li> <li><input disabled="" type="checkbox"> Expected VBE ≈ 0.7V for BJT</li> <li><input disabled="" type="checkbox"> Expected VCE between 0.1V and VCC-0.1V</li> <li><input disabled="" type="checkbox"> Expected VGS &gt; VTH for MOSFET</li> <li><input disabled="" type="checkbox"> Expected VDS in saturation region</li> </ul> <h3 id="--signal-path"> [ ] Signal Path <a class="anchor" href="#--signal-path">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Input clearly defined</li> <li><input disabled="" type="checkbox"> Output clearly defined</li> <li><input disabled="" type="checkbox"> Signal path continuous</li> <li><input disabled="" type="checkbox"> AC coupling capacitors where needed</li> <li><input disabled="" type="checkbox"> DC blocking verified</li> <li><input disabled="" type="checkbox"> Impedance matching considered</li> </ul> <hr> <h2 id="simulation-setup"> Simulation Setup <a class="anchor" href="#simulation-setup">#</a> </h2> <h3 id="--probe-placement"> [ ] Probe Placement <a class="anchor" href="#--probe-placement">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Input node probed</li> <li><input disabled="" type="checkbox"> Output node probed</li> <li><input disabled="" type="checkbox"> Critical intermediate nodes probed</li> <li><input disabled="" type="checkbox"> Power supply currents measured (if needed)</li> <li><input disabled="" type="checkbox"> Probe count within limits (2 for free, unlimited premium)</li> </ul> <h3 id="--analysis-type-selection"> [ ] Analysis Type Selection <a class="anchor" href="#--analysis-type-selection">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> <strong>DC Operating Point</strong>: for bias verification</li> <li><input disabled="" type="checkbox"> <strong>Transient</strong>: for time-domain signals</li> <li><input disabled="" type="checkbox"> <strong>AC Small-Signal</strong> (Premium): for frequency response</li> <li><input disabled="" type="checkbox"> Analysis type matches circuit goal</li> <li><input disabled="" type="checkbox"> Multiple analyses planned if needed</li> </ul> <h3 id="--analysis-parameters"> [ ] Analysis Parameters <a class="anchor" href="#--analysis-parameters">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> <strong>Transient</strong>: <ul> <li><input disabled="" type="checkbox"> Time step appropriate (1/100 of fastest signal)</li> <li><input disabled="" type="checkbox"> Stop time captures behavior (5-10 time constants)</li> <li><input disabled="" type="checkbox"> Initial conditions set if needed</li> </ul> </li> <li><input disabled="" type="checkbox"> <strong>AC Analysis</strong> (Premium): <ul> <li><input disabled="" type="checkbox"> Frequency range covers interest (0.1×fc to 10×fc)</li> <li><input disabled="" type="checkbox"> Points per decade sufficient (10-100)</li> <li><input disabled="" type="checkbox"> Source has AC magnitude set</li> </ul> </li> </ul> <hr> <h2 id="pre-simulation-checks"> Pre-Simulation Checks <a class="anchor" href="#pre-simulation-checks">#</a> </h2> <h3 id="--design-review"> [ ] Design Review <a class="anchor" href="#--design-review">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Circuit matches schematic/requirements</li> <li><input disabled="" type="checkbox"> Component count reasonable</li> <li><input disabled="" type="checkbox"> No obvious errors visible</li> <li><input disabled="" type="checkbox"> Similar to working examples</li> </ul> <h3 id="--common-pitfalls-avoided"> [ ] Common Pitfalls Avoided <a class="anchor" href="#--common-pitfalls-avoided">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> No voltage source loops (add series R)</li> <li><input disabled="" type="checkbox"> No current sources in series (add parallel R)</li> <li><input disabled="" type="checkbox"> No ideal shorts or opens</li> <li><input disabled="" type="checkbox"> No missing ground connections</li> <li><input disabled="" type="checkbox"> No reversed diodes/transistors</li> <li><input disabled="" type="checkbox"> No unrealistic component values</li> <li><input disabled="" type="checkbox"> No blocking capacitors in bias paths</li> </ul> <h3 id="--expected-results-defined"> [ ] Expected Results Defined <a class="anchor" href="#--expected-results-defined">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> DC voltages estimated</li> <li><input disabled="" type="checkbox"> AC gain calculated</li> <li><input disabled="" type="checkbox"> Frequency response predicted</li> <li><input disabled="" type="checkbox"> Time constants known</li> <li><input disabled="" type="checkbox"> Sanity check values ready</li> </ul> <hr> <h2 id="running-simulation"> Running Simulation <a class="anchor" href="#running-simulation">#</a> </h2> <h3 id="--start-simple"> [ ] Start Simple <a class="anchor" href="#--start-simple">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Run DC Operating Point first</li> <li><input disabled="" type="checkbox"> Verify DC voltages before AC/transient</li> <li><input disabled="" type="checkbox"> Check currents are reasonable</li> <li><input disabled="" type="checkbox"> Transistors in correct region (active/saturation)</li> </ul> <h3 id="--progressive-complexity"> [ ] Progressive Complexity <a class="anchor" href="#--progressive-complexity">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Simple analysis first</li> <li><input disabled="" type="checkbox"> Add complexity incrementally</li> <li><input disabled="" type="checkbox"> Verify at each step</li> <li><input disabled="" type="checkbox"> Don&rsquo;t skip validation</li> </ul> <h3 id="--monitor-warnings"> [ ] Monitor Warnings <a class="anchor" href="#--monitor-warnings">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Read all warning messages</li> <li><input disabled="" type="checkbox"> Understand each warning</li> <li><input disabled="" type="checkbox"> Fix warnings before accepting results</li> <li><input disabled="" type="checkbox"> Don&rsquo;t ignore convergence issues</li> </ul> <hr> <h2 id="results-verification"> Results Verification <a class="anchor" href="#results-verification">#</a> </h2> <h3 id="--sanity-checks"> [ ] Sanity Checks <a class="anchor" href="#--sanity-checks">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Results physically reasonable</li> <li><input disabled="" type="checkbox"> No violation of laws (KCL, KVL, power)</li> <li><input disabled="" type="checkbox"> Orders of magnitude correct</li> <li><input disabled="" type="checkbox"> Signs correct (phase, polarity)</li> </ul> <h3 id="--comparison-with-calculations"> [ ] Comparison with Calculations <a class="anchor" href="#--comparison-with-calculations">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> DC voltages match hand calculations (±10%)</li> <li><input disabled="" type="checkbox"> AC gain matches prediction</li> <li><input disabled="" type="checkbox"> Time constants correct (τ = RC or L/R)</li> <li><input disabled="" type="checkbox"> Cutoff frequencies as expected</li> </ul> <h3 id="--expected-behavior"> [ ] Expected Behavior <a class="anchor" href="#--expected-behavior">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Amplifier: output larger than input</li> <li><input disabled="" type="checkbox"> Filter: attenuation outside passband</li> <li><input disabled="" type="checkbox"> Oscillator: sustained oscillation</li> <li><input disabled="" type="checkbox"> Comparator: digital output</li> <li><input disabled="" type="checkbox"> Power supply: regulated output</li> </ul> <h3 id="--error-analysis"> [ ] Error Analysis <a class="anchor" href="#--error-analysis">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Results outside expectations investigated</li> <li><input disabled="" type="checkbox"> Discrepancies explained</li> <li><input disabled="" type="checkbox"> Model limitations understood</li> <li><input disabled="" type="checkbox"> Assumptions verified</li> </ul> <hr> <h2 id="documentation"> Documentation <a class="anchor" href="#documentation">#</a> </h2> <h3 id="--circuit-documented"> [ ] Circuit Documented <a class="anchor" href="#--circuit-documented">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> File saved with descriptive name</li> <li><input disabled="" type="checkbox"> Component values recorded</li> <li><input disabled="" type="checkbox"> Design rationale noted</li> <li><input disabled="" type="checkbox"> Calculation documented (separate file)</li> </ul> <h3 id="--results-recorded"> [ ] Results Recorded <a class="anchor" href="#--results-recorded">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Key waveforms captured (screenshot)</li> <li><input disabled="" type="checkbox"> Important values noted</li> <li><input disabled="" type="checkbox"> Analysis settings documented</li> <li><input disabled="" type="checkbox"> Anomalies documented</li> </ul> <h3 id="--design-decisions"> [ ] Design Decisions <a class="anchor" href="#--design-decisions">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Component choices justified</li> <li><input disabled="" type="checkbox"> Tradeoffs explained</li> <li><input disabled="" type="checkbox"> Alternative considered</li> <li><input disabled="" type="checkbox"> Future improvements noted</li> </ul> <hr> <h2 id="advanced-checks-premiumcomplex-circuits"> Advanced Checks (Premium/Complex Circuits) <a class="anchor" href="#advanced-checks-premiumcomplex-circuits">#</a> </h2> <h3 id="--sensitivity-analysis"> [ ] Sensitivity Analysis <a class="anchor" href="#--sensitivity-analysis">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Critical components identified</li> <li><input disabled="" type="checkbox"> Tolerance effects considered</li> <li><input disabled="" type="checkbox"> Monte Carlo run (if premium)</li> <li><input disabled="" type="checkbox"> Worst-case scenarios tested</li> </ul> <h3 id="--temperature-effects"> [ ] Temperature Effects <a class="anchor" href="#--temperature-effects">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Temperature range considered</li> <li><input disabled="" type="checkbox"> Coefficients set if known</li> <li><input disabled="" type="checkbox"> Temperature sweep run (if premium)</li> <li><input disabled="" type="checkbox"> Thermal stability verified</li> </ul> <h3 id="--frequency-effects"> [ ] Frequency Effects <a class="anchor" href="#--frequency-effects">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Parasitic capacitances considered</li> <li><input disabled="" type="checkbox"> High-frequency behavior verified</li> <li><input disabled="" type="checkbox"> Transmission line effects (if &gt;10MHz)</li> <li><input disabled="" type="checkbox"> Stability margins checked</li> </ul> <h3 id="--power-analysis"> [ ] Power Analysis <a class="anchor" href="#--power-analysis">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> Component power dissipation calculated</li> <li><input disabled="" type="checkbox"> Total power consumption noted</li> <li><input disabled="" type="checkbox"> Power ratings verified</li> <li><input disabled="" type="checkbox"> Heat dissipation considered</li> </ul> <hr> <h2 id="common-mistake-prevention"> Common Mistake Prevention <a class="anchor" href="#common-mistake-prevention">#</a> </h2> <h3 id="--avoided-these-common-errors"> [ ] Avoided These Common Errors <a class="anchor" href="#--avoided-these-common-errors">#</a> </h3> <ul> <li><input disabled="" type="checkbox"> ✓ Ground connected (not floating)</li> <li><input disabled="" type="checkbox"> ✓ Realistic component values</li> <li><input disabled="" type="checkbox"> ✓ Correct unit prefixes (k, M, m, μ)</li> <li><input disabled="" type="checkbox"> ✓ Diodes oriented correctly</li> <li><input disabled="" type="checkbox"> ✓ Transistor pins correct</li> <li><input disabled="" type="checkbox"> ✓ AC source for AC analysis</li> <li><input disabled="" type="checkbox"> ✓ Probes placed before running</li> <li><input disabled="" type="checkbox"> ✓ DC operating point verified first</li> <li><input disabled="" type="checkbox"> ✓ Simulation time window appropriate</li> <li><input disabled="" type="checkbox"> ✓ No blocking capacitors in bias</li> <li><input disabled="" type="checkbox"> ✓ Standard component values used</li> <li><input disabled="" type="checkbox"> ✓ Analysis type matches goal</li> </ul> <p>See <a href="https://breadpad.com/tutorials/common-mistakes/">Common Mistakes Guide</a> for details.</p>