Documentation sections

ADC SNR and ENOB Calculator

POSThttps://rftools.io/api/py/v1/calculate

Slug adc-snr. Calculate ADC signal-to-noise ratio, ENOB, and SFDR with aperture jitter effects. Analyze converter performance for data acquisition design. Free, instant results.

Inputs

Send every one of these in inputs, in the units shown. Most are required: a call without one is refused (400) and costs nothing; one the calculator can do without takes the default shown. An input outside its range is still computed and flagged in the provenance.

Inputs of adc-snr
Name	Unit	Range	Default	Description
bitsnumber	bits	1 … 24	12	ADC Resolution
inputFreqnumber	MHz	at least 0.001	1	Frequency of the input analog signal being sampled
samplingFreqnumber	MHz	at least 0.001	10	ADC sample rate. Each Nyquist zone is f_s/2 wide; an input above f_s/2 lies in a higher zone and folds to an alias below f_s/2
jitternumber	ps	at least 0.001	1	RMS aperture jitter of the ADC sampling clock in picoseconds
targetSnrnumber	dB	0 … 200	60	The signal-to-noise ratio the converter must reach. The status fails below 40 dB.

Outputs

Returned in values, by key. A value that is unbounded or undefined is null.

Outputs of adc-snr
Field	Unit	Description
theoreticalSnr	dB	Theoretical SNR (Quantization)
snrWithJitterheadline	dB	Effective SNR (with Jitter)
enob	bits	Effective Number of Bits
sfdr	dBc	SFDR (estimate)
noisePower	dBFS	Noise Floor
nyquistZone	none	The zone of width f_s/2 the input lies in; zone 1 runs from DC to f_s/2
aliasFrequency	MHz	Where the input appears after sampling: its image nearest DC, \|f_in − f_s·round(f_in/f_s)\|

Calling it

Calculate: one call, the request and response in full, and its errors.
Batch: this calculator with others, or a sweep, in one request.
Solve for a target: the value of one input that brings an output to a target.

curl -X POST https://rftools.io/api/py/v1/calculate \
  -H "X-API-Key: $RFTOOLS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "slug": "adc-snr",
    "inputs": {
      "bits": 12,
      "inputFreq": 1,
      "samplingFreq": 10,
      "jitter": 1,
      "targetSnr": 60
    }
  }'

import rftools

client = rftools.Client()  # reads RFTOOLS_API_KEY, or the key `rftools login` saved

result = client.calculate("adc-snr", {
    "bits": 12,
    "inputFreq": 1,
    "samplingFreq": 10,
    "jitter": 1,
    "targetSnr": 60,
})
print(result.values)
print(result.warnings, result.provenance.formula_ref)

const response = await fetch("https://rftools.io/api/py/v1/calculate", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.RFTOOLS_API_KEY,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "slug": "adc-snr",
    "inputs": {
      "bits": 12,
      "inputFreq": 1,
      "samplingFreq": 10,
      "jitter": 1,
      "targetSnr": 60
    }
  }),
});
console.log(response.status, await response.json());

package main

import (
	"bytes"
	"fmt"
	"io"
	"net/http"
	"os"
)

func main() {
	body := []byte(`{
	  "slug": "adc-snr",
	  "inputs": {
	    "bits": 12,
	    "inputFreq": 1,
	    "samplingFreq": 10,
	    "jitter": 1,
	    "targetSnr": 60
	  }
	}`)
	req, err := http.NewRequest("POST", "https://rftools.io/api/py/v1/calculate", bytes.NewReader(body))
	if err != nil {
		panic(err)
	}
	req.Header.Set("X-API-Key", os.Getenv("RFTOOLS_API_KEY"))
	req.Header.Set("Content-Type", "application/json")
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()
	out, _ := io.ReadAll(res.Body)
	fmt.Println(res.Status, string(out))
}

application/json

{
  "slug": "adc-snr",
  "values": {
    "theoreticalSnr": 74.0081115499123,
    "snrWithJitter": 74.00379894617443,
    "enob": 11.999283692024052,
    "sfdr": 111.01216732486844,
    "noisePower": -74.00379894617443,
    "nyquistZone": 1,
    "aliasFrequency": 1
  },
  "warnings": [],
  "errors": [],
  "provenance": {
    "method": "calculator:adc-snr",
    "version": "api@3f2c1a9b04de",
    "formulaRef": "Nyquist zones and alias: Kester, Analog Devices MT-002, Rev. A (10/08), Figure 5",
    "assumptions": [],
    "validRange": {
      "status": "inside",
      "bounds": {
        "bits": {
          "min": 1,
          "max": 24,
          "unit": "bits"
        },
        "inputFreq": {
          "min": 0.001,
          "max": null,
          "unit": "MHz"
        },
        "samplingFreq": {
          "min": 0.001,
          "max": null,
          "unit": "MHz"
        },
        "jitter": {
          "min": 0.001,
          "max": null,
          "unit": "ps"
        },
        "targetSnr": {
          "min": 0,
          "max": 200,
          "unit": "dB"
        }
      },
      "outside": [],
      "model": null
    },
    "computedAt": "2026-09-24T14:05:11.003Z",
    "inputs": {
      "bits": 12,
      "inputFreq": 1,
      "samplingFreq": 10,
      "jitter": 1,
      "targetSnr": 60
    },
    "seed": null,
    "elapsedSeconds": 0.003
  }
}

{
  "detail": [
    {
      "type": "float_parsing",
      "loc": [
        "body",
        "inputs",
        "bits"
      ],
      "msg": "Input should be a valid number, unable to parse string as a number",
      "input": "abc"
    }
  ]
}

An input sent as text. Nothing was counted.

{
  "detail": "More than 120 requests in 60 seconds from this address.",
  "errorKind": "rate_limited",
  "limit": 120,
  "windowSeconds": 60,
  "upgradeUrl": "https://rftools.io/pricing/"
}

Too many requests in a minute, with Retry-After.

Same inputs on the calculator pageADC SNR and ENOB Calculator, at these values