Op-Amp Gain Calculator (Inverting/Non-inverting/Diff)

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Electrical & Electronics Engineering — Circuits, Power Systems, Electronics Lab

Tranche

tranche-4

Evidence ID

t4-234

Ledger rows

1

No ledger note is attached.

Review findings

The stated gain equations are standard ideal formulas, but the specification is not complete enough for an unambiguous implementation. The exact ambiguity is the differential resistor labeling and missing R3/R4 inputs, plus undefined formulas for the promised impedance notes. Verdict requires review before release.

Formula and scope findings

• The inverting formula Av=-Rf/Rin and non-inverting formula Av=1+Rf/Rin are standard ideal closed-loop formulas, assuming Rin is nonzero and the op-amp remains in its linear operating region.
• The differential formula Vout=(R2/R1)(V2−V1) is standard only for a four-resistor difference amplifier with matched ratios, specifically R2/R1=R4/R3 under the usual resistor labeling. The second resistor pair and its labeling are not defined in the specification.
• The promised input/output impedance notes have no specified formulas or topology-dependent definitions. In particular, input impedance differs between inverting, non-inverting, and differential configurations.
• The specification does not define how gain and output should be reported when resistor values are zero, negative, non-finite, or supplied in inconsistent units.

Unit assumptions

• All resistor ratios are dimensionless; resistor values must use the same resistance unit after conversion, such as all ohms or all kilohms.
• Vin, V1, V2, and Vout are in volts.
• For the differential formula, R1 and R2 refer to the inverting-side input and feedback resistors, while R3 and R4 refer to the non-inverting-side resistor pair, with R2/R1=R4/R3.
• The ideal-op-amp impedance interpretation is infinite input impedance at the op-amp terminals and zero output impedance; the effective source impedance seen by each external input also depends on the resistor network.
• The calculations assume negative feedback, ideal resistors, and operation within the op-amp supply rails and common-mode range.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

A zero-valued Rin produces division by zero and an undefined gain/output; the instrument must reject that input rather than emit a numeric result.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "topology": "inverting",
    "Rf": 100000,
    "Rf_unit": "ohm",
    "Rin": 10000,
    "Rin_unit": "ohm",
    "Vin": 0,
    "Vin_unit": "V"
  },
  "expected_outputs": {
    "gain": -10,
    "Vout": 0,
    "impedance_notes": "Ideal model: source input impedance is approximately Rin = 10000 ohm; output impedance is 0 ohm."
  },
  "working": "Av = -Rf/Rin = -100000/10000 = -10. Vout = Av*Vin = (-10)*0 V = 0 V."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json