Lesson 1Calculating bandwidth and stability: closed-loop bandwidth from op-amp GBW, phase margin considerations, and compensation techniquesWe work out closed-loop bandwidth using op-amp gain-bandwidth and feedback, link phase margin to stability and response speed. We cover fixes for capacitive loads and high gains with practical tips.
Relate GBW, feedback factor, and bandwidthInterpret Bode plots and phase margin targetsIdentify signs of marginal or unstable loopsDesign compensation for capacitive loadingCheck stability across process and temperatureLesson 2Practical component selection: finding and interpreting op-amp datasheets (examples of sensor-grade amplifiers)This part shows how to check and pick op-amp datasheets for sensor work. Focus on noise, offset, input range, power options, and packages, plus quick ways to match parts to your setup needs.
Identify sensor-grade amplifier familiesInterpret input offset and drift specificationsEvaluate noise, CMRR, and PSRR parametersCheck input and output voltage rangesAssess package, power, and cost constraintsLesson 3SPICE simulation plan for amplifier block: stimulus sources (differential sine, common-mode, noise sources), AC analysis, transient, noise analysis, and offset/error measurementsThis part sets up a clear SPICE plan for the amplifier, with inputs, checks, and measures. Learn to confirm gain, bandwidth, noise, offset, and common-mode before PCB design.
Define simulation objectives and key metricsSet up differential and common-mode sourcesPlan AC, transient, and noise analysesMeasure gain, offset, and linearity in SPICEOrganize testbenches for reuse and reviewLesson 4Designing for input impedance: techniques to achieve high differential and common-mode input impedanceWe look at ways to get high input impedance for differential and common-mode using op-amp setups, buffers, and resistors, while managing bias currents, leaks, and bandwidth limits.
Define differential and common-mode impedanceUse buffer stages to isolate sensor loadingControl bias currents and leakage pathsGuarding and PCB techniques for high ZTrade-offs between impedance and bandwidthLesson 5Design documentation checklist: listing calculations, assumptions, part numbers, and margin analysis for PCB handoffThis part lists what to document for amplifier and sensor designs, including calcs, assumptions, parts, and safety margins so PCB and test teams can build and check confidently.
List design assumptions and operating conditionsRecord key equations and intermediate calculationsDocument part numbers and critical parametersCapture margin analysis and derating choicesDefine required tests and acceptance criteriaLesson 6Op-amp key parameters and selection process: input noise density, input bias current, input offset, GBW, slew rate, CMRR, PSRR, and supply rangeWe go over main op-amp specs for sensor interfaces and a steady pick process. Key focus on noise density, bias current, GBW, slew rate, CMRR, PSRR, and supply fit for your needs.
Relate GBW and slew rate to signal bandwidthUnderstand input noise density and filtersBias current and source impedance interactionCMRR, PSRR, and supply rejection needsStep-by-step op-amp selection checklistLesson 7Resistor networks and gain calculation for differential amplifiers and instrumentation amps: deriving gain equations and loading effectsWe figure gain formulas for differential and instrumentation amps, with resistor rules and loading. Stress on matching, CMRR, and how sensor/ADC loads change real gain.
Gain equations for basic differential stagesThree-op-amp instrumentation amp gain designImpact of resistor matching on CMRR and gainLoading from sensor and ADC input impedanceSelecting resistor values and power ratingsLesson 8Setting amplifier target specifications: gain, bandwidth, input impedance, offset, drift, and noise budgetThis shows how to turn sensor needs into amp targets for gain, bandwidth, impedance, offset, drift, noise. Make a short spec table to guide designs and parts.
Translate sensor and ADC requirementsDefine gain, bandwidth, and headroom limitsSet input impedance and loading constraintsAllocate offset and drift performance goalsCreate a formal amplifier spec tableLesson 9Understanding differential sensor signals: source impedance, common-mode, and differential-mode conceptsThis explains sensor signals, source impedance, common-mode, differential range. See how they impact noise, loading, amp choice, and reference setup.
Define differential and common-mode componentsCharacterize sensor source impedance vs frequencyDetermine allowable common-mode voltage rangeRelate sensor specs to amplifier input limitsPlan cabling, shielding, and reference routingLesson 10Topology selection for small differential signals: instrumentation amplifier, differential amplifier, and difference-stage with front-end buffer — trade-offs and use casesCompare in-amps, diff amps, buffered stages for small signals. Learn trade-offs in CMRR, noise, range, cost, layout for each type.
Review classic differential amplifier stageThree-op-amp instrumentation amplifier useBuffered difference stage with front-end gainCompare CMRR, noise, and input rangeGuidelines for topology selection by sensorLesson 11Offset and drift budgeting: calculating expected DC error from input offset, bias currents, resistor tolerances, and thermal effectsBuild DC error budget from op-amp offset, bias, resistor mismatch, temp drift. Set error limits, worst-case/RSS sums, link to sensor precision.
Define DC accuracy and allowable error budgetModel input offset and bias current effectsInclude resistor tolerance and mismatch termsAccount for temperature coefficients and driftCompare worst-case versus RSS error methodsLesson 12Noise sources in low-level signals: Johnson noise, amplifier input-referred noise, and environmental interferenceSpot and measure noise in sensor signals: resistor thermal, amp input noise, outside interference. Ways to model, budget, cut total noise.
Johnson noise of resistors and sensorsOp-amp voltage and current noise modelsInput-referred versus output noise conceptsEnvironmental and interference coupling pathsNoise budgeting and reduction strategiesLesson 13Expected simulation plots and measurements: gain vs frequency, phase, input-referred noise, output noise spectrum, transient response to 1 kHz sine, and worst-case offset scenariosKey plots and measures from sims and bench. Link Bode, noise spectra, transients, offsets to specs and budgets.
Gain and phase versus frequency Bode plotsInput-referred and output noise spectraTransient response to sine and step inputsOffset versus common-mode and temperatureCompare simulated and measured performance
