Chip information – Rainbow Electronics MAX1326 User Manual
Page 23
MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326
8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs
with ±10V, ±5V, and 0 to +5V Analog Input Ranges
______________________________________________________________________________________
23
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:
Effective Number of Bits
The effective number of bits (ENOB) indicates the global
accuracy of an ADC at a specific input frequency and
sampling rate. An ideal ADC’s error consists of quanti-
zation noise only. With an input range equal to the full-
scale range of the ADC, calculate the ENOB as follows:
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:
where V
1
is the fundamental amplitude and V
2
through
V
5
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.
Aperture Delay
Aperture delay (t
AD
) is the time delay from the sampling
clock edge to the instant when an actual sample is taken.
Aperture Jitter
Aperture Jitter (t
AJ
) is the sample-to-sample variation in
aperture delay.
Channel-to-Channel Isolation
Channel-to-channel isolation indicates how well each
analog input is isolated from the other channels. Channel-
to-channel isolation is measured by applying DC to chan-
nels 1 to 7, while a -0.5dBFS sine wave is applied to
channel 0. A 100kHz FFT is taken for channel 0 and
channel 1. Channel-to-channel isolation is expressed in
dB as the power ratio of the two 100kHz magnitudes.
Small-Signal Bandwidth
A small -20dBFS analog input signal is applied to an
ADC in a manner that ensures that the signal’s slew
rate does not limit the ADC’s performance. The input
frequency is then swept up to the point where the
amplitude of the digitized conversion result has
decreased 3dB.
Full-Power Bandwidth
A large -0.5dBFS analog input signal is applied to an
ADC, and the input frequency is swept up to the point
where the amplitude of the digitized conversion result
has decreased by 3dB. This point is defined as full-
power input bandwidth frequency.
Chip Information
TRANSISTOR COUNT: 80,000
PROCESS: BiCMOS 0.6µm
THD
V
V
V
V
V
=
×
+
+
+
⎡
⎣
⎢
⎢
⎢
⎤
⎦
⎥
⎥
⎥
20
2
2
3
2
4
2
5
2
1
log
ENOB
SINAD
=
- 1 76
6 02
.
.
SINAD dB
Signal
Noise
Distortion
RMS
RMS
(
)
log
(
)
=
Ч
+
⎡
⎣
⎢
⎤
⎦
⎥
20