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Op-amp Noise Calculator

Estimate flat-band output noise from en, optional in, gain, and bandwidth. Runs locally in your browser.

Instant result
Result
—

Enter values to calculate.

Inputs—
Mode—
Formula—
Trust summary CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance
Input interpretation
Enter values to calculate.
Result
—
Assurance
Engineering
Declared partition coverage
PASS · 2/2 declared partitions (noise, invalid-domain) · Matrix
Known limitations
  • Flat-band RSS; optional thermal on Rg
  • Core CVP does not include live graph, viewport, or pointer interaction.
Model
Flat-band op-amp output noise RMS.
Scope
White noise; ideal closed-loop G
Verification
Engine tested · Source checked · v1.0.0 · CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance· View Manifest · CVP overview · Specification
Versions
Calculation 1.0.0 · CVP protocol 1.0.0-proposed
CVP identity
1/1 property · digest 0e77adeee6a5
Legacy regression
5/5 tests · Production surface contract 4/4
Reference
O1 model · O2 expected_values · O2 numerical_behavior
Interfaces
PASS · UI (SSR) / REST / MCP — ui-ssr is query-result HTML, not a live browser session.
Supplemental domain review
Internal · Pass · electrical-engineer
Named expert review
Not performed
CVP suite
1/1 golden · 2/2 CVP boundary · 2/2 invalid · 1/1 property · 1/1 cross-interface · 1/1 CVP contract · Manifest
Sources
  • Op-amp noise design notes (TI/ADI style) — Broadband noise
  • Sedra/Smith — Microelectronic Circuits — Op-amp noise
Sources
Evidence
2 legacy golden · 2 legacy boundary · legacy regression suite · 1/1 oracle-backed golden · 2/2 invalid · Artifact integrity PASS · CalculatorX electrical review
This calculator CURRENT · Public schema 1.0.0 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓
Semantic contract
PASS
Full verification

Manifest identity, reference classes, interfaces, suite, and production records.

Formulas

Core equations used by this calculator.

Voltage noisee_n ≈ G·en·√BW
RSS combinee_out = √(e_en² + e_in² + e_th²)
iFlat-band / white-noise assumption. No 1/f corner in v1.

How to use

1

Choose the amplifier configuration

Gain from Rf/Rg sets noise gain for the estimate.

2

Enter voltage noise density en and bandwidth

en in nV/√Hz (as labeled) and BW > 0.

3

Optional: current noise and source resistance

When provided, in and Rsource contribute additional noise terms.

Example calculations

Common configurations with formula and result.

ϟ

en=10nV/√Hz

G=11 · BW=10kHz

11·10n·√10k
≈11 µVrms

Op-amp Noise calculator specification

Version 1.0.0 · Engine tested · Supplemental domain review · Internal · 2026-08-08

Calculation status

Review policy · Evidence · Reviewed by CalculatorX electrical review (electrical-engineer)

Definition
Closed-loop gain G maps input voltage noise density en through √BW to RMS. Optional current noise through Rsource and Rg thermal can be included.
What it calculates
Flat-band op-amp output noise RMS.
Inputs
  • mode
  • Rf
  • Rg
  • en
  • BW
  • optional in, Rsource
Outputs
  • e_n_out_rms
  • e_n_out_density
  • G_abs
Formula
G·en·√BW (+ in, thermal)
Assumptions
  • White noise; ideal closed-loop G
Units
  • V/√Hz, Hz → Vrms
Boundary conditions
  • en,BW,Rf,Rg ≤0 → VALUE_MUST_BE_POSITIVE
Example
en=1e-8 G=11 BW=10k → 11µVrms
Validation cases

1 published on this page · 5/5 tests · Production surface contract 4/4 · View evidence

  • Rf=10k Rg=1k en=1e-8 BW=1e4 → e_n_out_rms=1.1e-5
Sources
  • Op-amp noise design notes (TI/ADI style) — Broadband noise
    Supports: en·√BW·G referred to output
  • Sedra/Smith — Microelectronic Circuits — Op-amp noise
    Supports: Voltage/current density RSS to output
Last reviewed
2026-08-08
Reviewed by
CalculatorX electrical review (electrical-engineer)
Calculation version
1.0.0

Background

Interpretation and common distinctions.

Estimate op-amp broadband noise.

Supported and not supported

Supported — Flat-band en/in/thermal RSS · API electrical.opamp.noise

Not supported — 1/f corner, complex filters, measured FFT floors

Agent / API notes

Capability id: electrical.opamp.noise · tool id: opamp-noise · pin 1.0.0.

Errors: MISSING_REQUIRED_INPUT, VALUE_MUST_BE_POSITIVE, INVALID_MODE.

Other calculators in this family: ADC Error Budget Calculator, ADC SNR / Quantization Calculator, Op-amp Error Budget Calculator, Op-Amp Gain Calculator . Explore all Analog & Data Conversion.

→ ADC Error Budget Calculator Combine ADC gain, offset, INL, and DNL errors (RSS or worst-case) into total LSB, volts, and %FS. Runs locally in your browser. › → ADC SNR / Quantization Calculator Ideal quantization SNR ≈ 6.02·N + 1.76 dB for a full-scale sine; reverse measured SINAD to ENOB. Runs locally in your browser. › → Op-amp Error Budget Calculator Estimate DC output-referred error from Vos, Ib, Ios and feedback resistors (RSS or worst-case). › → Op-Amp Gain Calculator Closed-loop gain for non-inverting (1+Rf/Rg) and inverting (−Rf/Rg) op-amp circuits. Runs locally in your browser. ›
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Frequently asked questions

Key distinctions behind the calculation.

Does this include 1/f noise?

No — v1 is flat-band only. Integrate a 1/f model separately if needed.