Lesson 1Working out bandwidth and stability: closed-loop bandwidth from op-amp GBW, phase margin checks, and ways to compensateWe work out closed-loop bandwidth using the op-amp's gain-bandwidth product and feedback factor, then link phase margin to stability and how it responds over time. We cover options for handling 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 2Picking components in practice: finding and reading op-amp datasheets (examples with sensor-grade amplifiers)This part teaches you how to go through and compare op-amp datasheets for sensor work. You'll look at noise, offset, input range, power options, and packaging, and get quick ways to pick parts that fit your system's 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: input signals (differential sine, common-mode, noise), AC checks, transient, noise analysis, and offset/error testsThis part builds a proper SPICE plan for the amplifier section, setting up inputs, checks, and measurements. You'll see how to confirm gain, bandwidth, noise, offset, and common-mode performance before laying out the PCB.
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: methods to get high differential and common-mode input impedanceWe look at ways to get high input impedance for differential and common-mode signals with op-amp setups, buffers, and resistor picks, while keeping bias currents, leaks, and bandwidth under control.
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 notes checklist: listing calculations, assumptions, part numbers, and margin checks for PCB handoverThis part sets up a solid set of design notes for amplifier and sensor front-ends, noting down calculations, assumptions, parts, and safety margins so PCB teams can build and check the circuit with confidence.
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 picking process: input noise density, bias current, offset, GBW, slew rate, CMRR, PSRR, and supply rangeWe go over the main op-amp specs for small-signal sensor setups and create a reliable way to pick them. Focus is 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 setups and gain calculations for differential amps and instrumentation amps: working out gain formulas and loading effectsWe work out gain formulas for standard differential and instrumentation amp setups, including resistor limits and loading. Key points are matching, CMRR, and how sensor/ADC impedances change the actual 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 goals: gain, bandwidth, input impedance, offset, drift, and noise allowanceThis part shows how to turn system sensor needs into amplifier targets for gain, bandwidth, input impedance, offset, drift, and noise. You'll make a short specs table to guide your setup and part choices.
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 ideasThis part explains how differential sensors work, covering source impedance, common-mode level, and signal range. You'll see how these affect noise, loading, and choices for amp setup and reference.
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 10Picking setups for small differential signals: instrumentation amp, differential amp, and difference stage with front buffer — pros, cons, and when to useThis part compares instrumentation amps, standard differential amps, and buffered difference stages for small signals. You'll learn trade-offs in CMRR, noise, input range, cost, and layout for each one.
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 planning: calculating expected DC errors from input offset, bias currents, resistor tolerances, and heat effectsHere we put together a DC error plan, mixing op-amp offset, bias currents, resistor mismatches, and temp drift. You'll set error limits, work out worst-case and typical totals, and 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-referred noise, and outside interferenceWe spot and measure noise in low-level sensor signals, like resistor heat noise, amp input noise, and outside pickup. We cover ways to model, plan, and 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 graphs and measurements: gain vs frequency, phase, input-referred noise, output noise spectrum, response to 1 kHz sine, and worst-case offset casesThis part lists key graphs and measurements from sims and bench tests. You'll tie Bode plots, noise spectra, transients, and offset checks back to original specs and error plans.
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
