ADC SNR, ENOB & Jitter
Estimates the dynamic performance of an analog-to-digital converter. The ideal quantization SNR sets the ceiling for an N-bit converter; sampling-clock aperture jitter adds a noise floor that grows with input frequency. The two combine to a realistic SNR, from which the effective number of bits (ENOB) follows. Enter a measured SINAD to get ENOB directly.
Equations & Parameters ▸
\(\text{SNR}_{\text{q}} = 6.02\,N + 1.76\ \text{dB} \qquad \text{SNR}_{\text{jitter}} = -20\log_{10}\!\big(2\pi f_{\text{in}}\,\sigma_t\big)\)
\(\text{SNR}_{\text{total}} = -10\log_{10}\!\big(10^{-\text{SNR}_q/10} + 10^{-\text{SNR}_{\text{jitter}}/10}\big) \qquad \text{ENOB} = \dfrac{\text{SINAD} - 1.76}{6.02}\)
\(\text{SNR}_{\text{total}} = -10\log_{10}\!\big(10^{-\text{SNR}_q/10} + 10^{-\text{SNR}_{\text{jitter}}/10}\big) \qquad \text{ENOB} = \dfrac{\text{SINAD} - 1.76}{6.02}\)
| N | Converter resolution (bits). |
| fin | Analog input (signal) frequency (MHz). |
| σt | RMS aperture (sample-clock) jitter, in picoseconds. |
| SINAD | Measured signal-to-noise-and-distortion (dB), optional. If given, ENOB is taken from it. |
| ENOB | Effective number of bits — the resolution of an ideal converter with the same SNR. |
References: W. Kester (ed.), Data Conversion Handbook, Analog Devices/Newnes, 2005. · IEEE Std 1241-2010, Terminology and Test Methods for Analog-to-Digital Converters.
Inputs
bits
Converter bitsMHz
Signal frequencyps
RMS clock jitterdB
For measured ENOBResults
SNR contributions
Quantization SNR—
Jitter-limited SNR—
Combined SNR—
Effective resolution
ENOB—
Limited by—
Diagram