MAX11101 Datasheet, PDF (17/19 Pages) Maxim Integrated Products – 14-Bit, +5V, 200ksps ADC with 10μA Shutdown

MAX11101
14-Bit, +5V, 200ksps ADC with 10µA Shutdown
Definitions
Integral Nonlinearity
Integral nonlinearity (INL) is the deviation of the values
on an actual transfer function from a straight line. This
straight line can be either a best-fit straight line fit or a line
drawn between the end points of the transfer function,
once offset and gain errors have been nullified. The static
linearity parameters for the MAX11101 are measured
using the endpoint method.
Differential Nonlinearity
Differential nonlinearity (DNL) is the difference between
an actual step width and the ideal value of 1 LSB. A DNL
error specification of 1 LSB guarantees no missing codes
and a monotonic transfer function.
Aperture Definitions
Aperture jitter (t_AJ) is the sample-to-sample variation in
the time between samples. Aperture delay (t_AD) is the
time between the falling edge of the sampling clock and
the instant when the actual sample is taken.
Signal-to-Noise Ratio
For a waveform perfectly reconstructed from digital
samples, signal-to-noise ratio (SNR) is the ratio of the
full-scale analog input (RMS value) to the RMS quantiza-
tion error (residual error). The ideal, theoretical minimum
analog-to-digital noise is caused by quantization noise
error only and results directly from the ADCs resolution
(N bits):
SNR = (6.02 x N + 1.76)dB
In reality, there are other noise sources besides quantiza-
tion noise: thermal noise, reference noise, clock jitter, etc.
SNR is computed by taking the ratio of the RMS signal to
the RMS noise, which includes all spectral components
minus the fundamental, the first five harmonics, and the
DC offset.
Signal-to-Noise Plus Distortion
Signal-to-noise plus distortion (SINAD) is the ratio of the
fundamental input frequency’s RMS amplitude to the
RMS equivalent of all the other ADC output signals.
SINAD(dB=)
20
×
log^{}_(NoiseS+^igDnisatloR_r^M_tio^S_n)RMS



Effective Number of Bits
Effective number of bits (ENOB) indicate the global
accuracy of an ADC at a specific input frequency and
sampling rate. An ideal ADC error consists of quantiza-
tion noise only. With an input range equal to the full-scale
range of the ADC, calculate the effective number of bits
as follows:
ENOB = (SINAD – 1.76)/6.02
Figure 13 shows the effective number of bits as a function
of the MAX11101’s input frequency.
Total Harmonic Distortion
Total harmonic distortion (THD) is the ratio of the RMS
sum of the first five harmonics of the input signal to the
fundamental itself. This is expressed as:
THD=

20 × log^
V₂ ²
+
V₃ ²
+
V₄ ²
+
V₅ ²



V1



where V₁ is the fundamental amplitude and V₂ through
V₅ are the 2nd- through 5th-order harmonics.
Spurious-Free Dynamic Range
Spurious-free dynamic range (SFDR) is the ratio of the
RMS amplitude of the fundamental (maximum signal
component) to the RMS value of the next largest fre-
quency component.
14
12
10
8
6
4
2
fSAMPLE = 200kHz
0
0.1
1
10
100
INPUT FREQUENCY (kHz)
Figure 13. Effective Number of Bits vs. Input Frequency
���������������������������������������������������������������� Maxim Integrated Products  17