Lesson 1Working out bandwidth and stability: closed-loop bandwidth from op-amp GBW, phase margin checks, and compensation methodsWe work out closed-loop bandwidth from op-amp gain-bandwidth product and feedback factor, linking phase margin to stability and response. Compensation for capacitive loads and high gains comes with practical design 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 2Picking components in practice: reading and understanding op-amp datasheets (examples with sensor-grade amps)This bit teaches you how to go through op-amp datasheets for sensor conditioning. Focus on noise, offset, input range, supply choices, packaging, and quick screening against your system 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 setup for amplifier block: stimulus sources (differential sine, common-mode, noise), AC analysis, transient, noise checks, and offset/error measurementsThis section puts together a proper SPICE plan for the amplifier block, setting stimuli, analyses, and measurements. You'll check gain, bandwidth, noise, offset, and common-mode before PCB layout.
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: ways to get high differential and common-mode input impedanceWe look at achieving high input impedance for differential and common-mode signals with op-amp inputs, buffers, and resistor picks, 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 checks for PCB handoffThis section lays out a solid documentation package for amplifier and sensor front-ends, noting calculations, assumptions, parts, and 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 specs and selection: input noise density, bias current, offset, GBW, slew rate, CMRR, PSRR, supply rangeWe go over vital op-amp specs for small-signal sensors and create a repeatable pick process. Focus on noise density, bias current, GBW, slew rate, CMRR, PSRR, and supply matching 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 for differential amps and in-amps: gain equations and loading effectsWe derive gain equations for standard differential and instrumentation amp setups, including resistor constraints and loading. Key points on matching, CMRR, and sensor/ADC impedances changing 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 specs: gain, bandwidth, input impedance, offset, drift, noise budgetThis section shows turning system sensor needs into amplifier targets for gain, bandwidth, impedance, offset, drift, noise. You'll make a clear spec table to guide topology 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, differential-mode basicsThis section covers differential sensor behaviour, source impedance, common-mode level, signal range. See how these hit noise, loading, amp topology, and reference choices.
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 choices for small differential signals: in-amp, diff amp, difference-stage with buffer — trade-offs and casesThis section compares in-amps, diff amps, buffered difference stages for small signals. Trade-offs in CMRR, noise, input range, cost, layout for each setup.
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 DC error from offset, bias currents, resistor tolerances, thermal effectsHere we make a DC error budget from op-amp offset, bias, resistor mismatch, temp drift. Allocate limits, worst-case and RSS totals, link to sensor accuracy.
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, amp input noise, environmental interferenceWe spot and measure noise in low sensor signals: resistor thermal, amp input noise, interference. Methods for modelling, budgeting, cutting total noise introduced.
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 noise, output spectrum, transient to 1 kHz sine, worst-case offsetThis section sets key plots and measurements from sims and bench. Link Bode, noise spectra, transients, offset sweeps to specs and error 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
