Source: https://guthlabs.ai/docs/instruments/op-amp-bandwidth-gain-bandwidth-product-checker/
instrument / verified-clean
# Op-Amp Bandwidth / Gain-Bandwidth Product Checker
The current ledger marks this instrument verified clean within the source-bound verification corpus.
Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**
## Inspectable records
[01**Overview**Purpose and lifecycle]()[02**Mechanism**Method and assumptions]()[03**Implementation**Binding and validation]()[04**Qualification**Evidence and errata]()
## 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**: t4-257
**Ledger rows**: 1
No ledger note is attached.
## Review findings
The arithmetic formula is acceptable as a first-order estimate only after the gain definition, units, and op-amp model are made explicit. The empty honest_label is a concern: the interface should state that this is an approximate GBW-based estimate, not a guaranteed usable bandwidth.
### Formula and scope findings
- BW=GBW/Av is a standard first-order approximation for a voltage-feedback op-amp with a single dominant pole, where Av is the positive closed-loop noise gain magnitude, not necessarily the signal gain magnitude.
- For an inverting amplifier, the relevant gain for bandwidth is the noise gain 1+Rf/Rin, not the magnitude of the signal gain Rf/Rin.
- The label 'maximum usable closed-loop bandwidth' is too strong: actual bandwidth also depends on compensation, additional poles, feedback network loading, capacitive loading, stability margin, slew rate, output amplitude, and the required accuracy.
- The requested 'feasibility warning' has no defined input target bandwidth or warning threshold, so the instrument cannot determine feasibility from the supplied inputs alone.
- The specification does not define valid gain constraints; zero gain causes division by zero, and negative or nonnumeric gain values are ambiguous.
### Unit assumptions
- GBW and the resulting bandwidth must use the same frequency unit; the test outputs below normalize bandwidth to Hz.
- Av must be a dimensionless voltage gain magnitude expressed as V/V, not dB.
- The formula assumes a voltage-feedback op-amp with approximately constant gain-bandwidth product and a dominant-pole response.
- For an inverting configuration, Av must be interpreted as noise gain rather than signal gain.
- The formula estimates the approximate closed-loop -3 dB bandwidth, not a guaranteed usable bandwidth under all load, amplitude, accuracy, or stability conditions.
## Boundary hardening
**BREAK_CLAIMED** · SELF_FLAGGED
The formula is undefined when desired gain is zero, so the instrument must reject Av = 0 or explicitly report an undefined result. The specification also does not define a formula branch, a feasibility-warning threshold, or whether gain should be signed or treated by magnitude.
## 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": {
"gbw": 1,
"gbw_unit": "MHz",
"desired_gain": 10
},
"expected_outputs": {
"achievable_bandwidth": 100000,
"bandwidth_unit": "Hz",
"feasibility_warning": "Cannot be determined: no target bandwidth or feasibility criteria were supplied."
},
"working": "1 MHz = 1,000,000 Hz. BW = GBW / Av = 1,000,000 Hz / 10 = 100,000 Hz."
}
````
## 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`