Lesson 1Working out bandwidth and stability: closed-loop bandwidth from op-amp GBW, phase margin ideas, and fixing techniquesWe work out closed-loop bandwidth from op-amp gain-bandwidth product and feedback factor, then link phase margin to stability and quick response. Fixing options for capacitive loads and high gains are shown with design tips.
Link GBW, feedback factor, and bandwidthRead Bode plots and phase margin goalsSpot signs of weak or unstable loopsPlan fixes for capacitive loadingCheck stability over process and temperatureLesson 2Practical part picking: finding and reading op-amp datasheets (examples of sensor-grade amplifiers)This part teaches how to read and compare op-amp datasheets for sensor handling. You will look at noise, offset, input range, supply choices, and packaging, and learn to check parts fast against system needs.
Spot sensor-grade amplifier familiesRead input offset and drift specsCheck noise, CMRR, and PSRR parametersLook at input and output voltage rangesWeigh package, power, and cost limitsLesson 3SPICE simulation plan for amplifier block: stimulus sources (differential sine, common-mode, noise sources), AC analysis, transient, noise analysis, and offset/error measurementsThis part builds a proper SPICE plan for the amplifier block, setting stimuli, analyses, and checks. You will learn how to confirm gain, bandwidth, noise, offset, and common-mode action before PCB layout.
Set simulation goals and key measuresPrepare differential and common-mode sourcesPlan AC, transient, and noise analysesMeasure gain, offset, and linearity in SPICEArrange testbenches for reuse and checkLesson 4Designing for input impedance: ways to get high differential and common-mode input impedanceWe look at how to get high input impedance for differential and common-mode signals using op-amp input setups, buffer stages, and resistor picks, while managing bias currents, leak paths, and bandwidth limits.
Define differential and common-mode impedanceUse buffer stages to avoid sensor loadingManage bias currents and leak pathsGuarding and PCB ways for high ZBalance between impedance and bandwidthLesson 5Design notes checklist: listing calculations, assumptions, part numbers, and margin analysis for PCB handoffThis part sets a strong notes package for amplifier and sensor front-end designs, noting calculations, assumptions, part picks, and margins so PCB, layout, and test teams can build and check the circuit with confidence.
List design assumptions and working conditionsNote key equations and middle calculationsDocument part numbers and vital parametersCapture margin analysis and derating picksSet required tests and acceptance rulesLesson 6Op-amp key parameters and picking process: input noise density, input bias current, input offset, GBW, slew rate, CMRR, PSRR, and supply rangeWe review vital op-amp parameters for small-signal sensor links and build a repeatable picking process. Focus is on noise density, bias current, GBW, slew rate, CMRR, PSRR, and supply range against application needs.
Link GBW and slew rate to signal bandwidthUnderstand input noise density and filtersBias current and source impedance mixCMRR, PSRR, and supply rejection needsStep-by-step op-amp picking checklistLesson 7Resistor networks and gain calculation for differential amplifiers and instrumentation amps: deriving gain equations and loading effectsWe work out gain equations for classic differential and instrumentation amplifier setups, including resistor network limits and loading. Focus is on matching, CMRR, and how sensor and ADC impedances change effective 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 impedancePicking resistor values and power ratingsLesson 8Setting amplifier target specifications: gain, bandwidth, input impedance, offset, drift, and noise budgetThis part shows how to turn system-level sensor needs into amplifier targets for gain, bandwidth, input impedance, offset, drift, and noise. You will make a short spec table to guide setup and part picks.
Turn sensor and ADC needs into targetsSet gain, bandwidth, and headroom limitsSet input impedance and loading limitsAssign offset and drift performance goalsMake a formal amplifier spec tableLesson 9Understanding differential sensor signals: source impedance, common-mode, and differential-mode conceptsThis part explains differential sensor action, including source impedance, common-mode level, and differential signal range. You will learn how these affect noise, loading, and choice of amplifier setup and reference plan.
Define differential and common-mode partsDescribe sensor source impedance vs frequencyFind allowable common-mode voltage rangeLink sensor specs to amplifier input limitsPlan cabling, shielding, and reference routingLesson 10Setup picking for small differential signals: instrumentation amplifier, differential amplifier, and difference-stage with front-end buffer — trade-offs and use casesThis part compares instrumentation amplifiers, classic differential amplifiers, and buffered difference stages for small differential signals. You will learn trade-offs in CMRR, noise, input range, cost, and layout complexity 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 setup picking by sensorLesson 11Offset and drift budgeting: calculating expected DC error from input offset, bias currents, resistor tolerances, and thermal effectsHere we build a number-based DC error budget, mixing op-amp offset, bias currents, resistor mismatch, and temperature drift. You will learn to assign error limits, compute worst-case and RSS totals, and link them 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, amplifier input-referred noise, and environmental interferenceWe spot and measure noise sources in low-level sensor signals, including resistor thermal noise, amplifier input noise, and outside interference. Ways for modeling, budgeting, and cutting total noise are shown.
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 scenariosThis part sets the key plots and checks expected from simulation and bench work. You will link Bode plots, noise spectra, transient responses, and offset sweeps to the original specs and error budgets for the design.
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
