Lesson 1Working out bandwidth and stability: closed-loop bandwidth from op-amp GBW, phase margin checks, and ways to compensateWe figure out closed-loop bandwidth from the op-amp's gain-bandwidth product and feedback setup, 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: reading and understanding op-amp datasheets (examples with sensor-friendly amps)This part teaches you how to go through op-amp datasheets for sensor work. You'll look at noise, offset, input range, power options, and packaging, learning 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 sim plan for the amp section: input signals (differential sine, common-mode, noise), AC checks, transient, noise analysis, and offset/error testsThis part builds a clear SPICE plan for the amp block, setting up inputs, analyses, and checks. 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 4Setting up for high input impedance: methods to get good 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 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 notes checklist: jotting down calculations, assumptions, part numbers, and safety margins for PCB handoverThis part sets up a solid set of design notes for amp and sensor front-ends, noting calculations, assumptions, parts, and 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 6Key op-amp specs and picking process: input noise density, bias current, offset, GBW, slew rate, CMRR, PSRR, supply rangeWe go over main op-amp specs for small-signal sensor setups and create a steady 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 figuring for differential amps and in-amps: gain formulas and loading impactsWe work out gain formulas for standard differential and instrumentation amp setups, including resistor rules and loading. Key points are matching, CMRR, and how sensor/ADC loads change the 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 amp goals: gain, bandwidth, input impedance, offset, drift, noise allowanceThis part shows how to turn system sensor needs into amp targets for gain, bandwidth, input impedance, offset, drift, and noise. You'll make a short specs table to guide setups 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 9Getting differential sensor signals: source impedance, common-mode, differential-mode ideasThis part explains how differential sensors work, covering source impedance, common-mode level, and signal range. You'll learn how these affect noise, loading, and amp setup plus 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 10Picking setups for small differential signals: in-amp, differential amp, difference stage with buffer — pros, cons, usesThis part compares in-amps, standard differential amps, and buffered difference stages for tiny signals. You'll see trade-offs in CMRR, noise, input range, cost, and layout ease for each.
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: figuring DC errors from input offset, bias currents, resistor mismatches, heat effectsWe put together a numbers-based DC error plan, mixing op-amp offset, bias currents, resistor differences, and temp drift. You'll set error limits, calculate worst-case and combined totals, linking 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 in quiet signals: Johnson noise, amp input noise, outside interferenceWe spot and measure noise in low-level sensor signals, like resistor heat noise, amp input noise, and outside bother. Ways to model, plan, and cut total noise are covered.
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 13What sim plots and checks to expect: gain vs frequency, phase, input noise, output noise graph, response to 1 kHz sine, worst offset casesThis part lists key plots and checks from sims and bench tests. You'll tie Bode plots, noise graphs, time responses, and offset runs 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
