MAX1183
(1Ω to 5Ω), a ferrite bead, or a direct short. Alternatively,
all ground pins could share the same ground plane, if the
ground plane is sufficiently isolated from any noisy, digital
systems ground plane (e.g. downstream output buffer or
DSP ground plane). Route high-speed digital signal
traces away from the sensitive analog traces of either
channel. Make sure to isolate the analog input lines to
each respective converter to minimize channel-to-chan-
nel crosstalk. Keep all signal lines short and free of 90
degree turns.
Static Parameter Definitions
Integral Nonlinearity (INL)
Integral nonlinearity is the deviation of the values on an
actual transfer function from a straight line. This straight
line can be either a best straight-line fit or a line drawn
between the endpoints of the transfer function, once
offset and gain errors have been nullified. The static lin-
earity parameters for the MAX1183 are measured using
the best straight-line fit method.
Differential Nonlinearity (DNL)
Differential nonlinearity is the difference between an
actual step width and the ideal value of 1LSB. A DNL
error specification of less than 1LSB guarantees no
missing codes and a monotonic transfer function.
Dynamic Parameter Definitions
Aperture Jitter
Figure 9 depicts the aperture jitter (t
AJ
), which is the
sample-to-sample variation in the aperture delay.
Aperture Delay
Aperture delay (t
AD
) is the time defined between the
falling edge of the sampling clock and the instant when
an actual sample is taken (Figure 9).
Signal-to-Noise Ratio (SNR)
For a waveform perfectly reconstructed from digital sam-
ples, the theoretical maximum SNR is the ratio of the full-
scale analog input (RMS value) to the RMS quantization
error (residual error). The ideal, theoretical minimum ana-
log-to-digital noise is caused by quantization error only
and results directly from the ADC’s resolution (N-Bits):
SNR
dB[max]
= 6.02 ✕ N + 1.76
In reality, there are other noise sources besides quanti-
zation 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 har-
monics, and the DC offset.
Dual 10-Bit, 40Msps, 3V, Low-Power ADC with
Internal Reference and Parallel Outputs
16 ______________________________________________________________________________________
