Home

SNDR

SNDR stands for signal-to-noise-and-distortion ratio. It is a measure of how much of the desired signal remains relative to the combined power of noise and distortion within a defined bandwidth. Expressed in decibels, SNDR = 10 log10(P_signal / (P_noise + P_distortion)).

The metric is commonly used to characterize the linearity and dynamic performance of analog-to-digital converters (ADCs),

SNDR is closely related to other performance metrics. When interference is negligible, SNDR approximates SINAD (signal-to-noise-and-distortion-and-interference).

Typical SNDR values vary with technology, sampling rate, and test conditions. High-performance ADCs may exhibit SNDR

In summary, SNDR provides a single, bandwidth-specific indication of how clean the output signal remains in

digital-to-analog
converters
(DACs),
amplifiers,
and
RF
front-ends.
In
testing,
a
known
input
signal
is
applied
and
the
output
is
analyzed
with
a
spectrum
or
FFT.
The
power
of
the
fundamental
signal
is
compared
with
the
aggregate
power
of
noise
and
distortion
products,
including
harmonics
and
intermodulation
components,
within
the
specified
bandwidth.
ENOB
(effective
number
of
bits)
can
be
derived
from
SNDR
using
the
approximate
relation
ENOB
=
(SNDR
−
1.76)
/
6.02,
where
the
constants
reflect
the
theoretical
quantization
noise
of
an
ideal
ADC.
in
the
range
of
70
to
90
dB
or
higher
under
suitable
conditions,
while
consumer-grade
components
may
show
lower
values.
Because
SNDR
is
bandwidth-dependent,
the
reported
figure
should
specify
the
measurement
bandwidth
and
test
method.
the
presence
of
noise
and
nonlinear
distortion,
and
it
underpins
the
evaluation
and
comparison
of
precision
electrical
and
mixed-signal
devices.