Cascaded Noise Figure Calculator

A Friis formula-based tool for calculating the noise figure of multistage RF systems, supporting cascaded analysis of LNAs and mixers.

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Speed and Stability: Processing speed depends on your device and browser. For large batch work, the desktop version may be more stable.

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If the online tool fails to load or run, try the desktop tool.https://tools.yikeaigc.com/

Tool Usage

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Select a link template or enter each stage's parameters, then calculate and export the results.

Ideal for noise budgeting of multistage links such as receiver front ends, LNAs, filters, mixers, and IF amplifiers. Calculations use the Friis cascaded noise formula, with gains and losses entered in dB.

Friis Formula Noise Temperature Contribution JSON Batch Compare Settings can be saved

Core Formula F = F1 + (F2 - 1) / G1 + (F3 - 1) / (G1 * G2) + ... F is the linear noise factor, and G is the linear power gain. Noise figure NF(dB) = 10 log10(F), equivalent noise temperature Te = (F - 1) T0.

Set Link

Load an example or preset template first, then adjust it with actual device data. Enter negative gain for passive lossy devices; their noise figure is usually equal to insertion loss.

Base ParametersSet the system type and stage count first

System Type

Cascade Stages

Plan Name

Frequency Unit

Preset TemplateClicking will overwrite the current table

Cascade parameter table Noise figure and gain are required; P1dB/IP3/frequency are for records and export

Stage	Device type	Name	Noise figure dB	Gain dB	P1dB dBm	IP3 dBm	Frequency	Action

Calculation Options

Set reference temperature, display precision, and batch comparison data. Manual and batch schemes are calculated locally.

Output settingsEngineering reports usually use 3 or 4 decimals

Reference temperature T0 Unit K; standard noise temperature commonly uses 290K.

Decimal places

Batch sort

NF warning threshold Show optimization tips above this dB value.

Auto calculate Show linear values Show noise temperature Show contribution share

Batch JSON compareOptional: compare multiple link plans side by side

Batch config

Batch actions Batch results can be copied, downloaded as CSV, or loaded back to the table for fine-tuning.

Plan	Stage	Total NF dB	Total gain dB	Noise factor	Noise temp K	Dominant stage	Action

Export Results

After calculating, view total noise figure, total gain, noise temperature, stage contributions, and trend charts. Copy results or download CSV, JSON, or SVG reports.

Export & reuseCalculate before exporting

Set link parameters first, then go to calculation options and view results.

Calculation preview

Total noise figure-dB

Total gain-dB

Noise factor-Linear

Equivalent noise temperature-K

Cumulative NF & gain trend

Analysis tips

Load an example or enter valid parameters for at least 2 stages, then click Calculate to view the link noise budget.

Dominant stage

Waiting for calculation.

Optimization tips

Usually focus first on front-end loss, LNA noise figure, and front-end gain.

Stage	Device	NF dB	Gain dB	Linear F	Linear G	Friis term	Contribution	Cumulative NF dB	Cumulative gain dB	Cumulative temp K
Waiting for results

Instructions

Software Usage Instructions

Set link parameters: Select the system type, number of cascade stages, scheme name, and frequency unit, or directly load preset templates such as receiver front end, LNA + mixer, or radar front end.
Enter data for each device stage: Enter the device type, name, noise figure NF(dB), and gain(dB). For lossy devices such as filters, attenuators, and cables, enter the gain as a negative value.
Configure calculation options: Set the reference temperature T0, decimal places, and NF warning threshold, and choose whether to display linear values, noise temperature, and contribution percentage.
Perform batch comparison: To compare multiple schemes, enter multiple sets of stages data in the batch JSON area and click “Batch Calculate” to view the total NF, total gain, and dominant contribution stage for different schemes.
View results: After clicking “Calculate Noise Figure”, you can view the total noise figure, total gain, noise factor, equivalent noise temperature, Friis term for each stage, and cumulative trend chart.
Export and save: Supports copying results, downloading CSV, downloading JSON, downloading SVG charts, and saving the current settings for continued use later.

FAQ

A: The Friis formula is suitable for estimating the total noise figure of multi-stage RF links, such as receiver chains where an LNA, filter, mixer, IF amplifier, and other components are cascaded in sequence.

A: The noise factor F is a linear value, while the noise figure NF is a decibel value. The conversion is NF(dB)=10×log10(F). The tool provides both types of results.

A: Enter the gain of a lossy device as a negative value. For example, enter a 2dB insertion loss as -2dB. Under normal-temperature matched conditions, the noise figure of a passive lossy device can usually be entered as the loss value, such as 2dB.

A: In the Friis formula, the noise contribution of later stages is scaled by the gain of the preceding stages, so the noise figure and gain of the earlier stages significantly affect the total noise budget.

A: The equivalent noise temperature Te is used to describe noise performance in terms of temperature, with the relationship Te=(F-1)×T0. In satellite communications, low-noise receiving, and radio astronomy systems, both NF and Te are often considered.