Rainbow Electronics MAX106 - Manual (Page 27)

MAX106
±5V, 600Msps, 8-Bit ADC with On-Chip
2.2GHz Bandwidth Track/Hold Amplifier
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Bit Error Rates (BERs)
Errors resulting from metastable states may occur when
the analog input voltage (at the time the sample is
taken) falls close to the decision point of any one of the
input comparators. Here, the magnitude of the error
depends on the location of the comparator in the com-
parator network. If it is the comparator for the MSB, the
error will reach full scale. The MAX106’s unique encod-
ing scheme solves this problem by virtually eliminating
these errors.
Dynamic Parameter Definitions
Signal-to-Noise Ratio
For a waveform perfectly reconstructed from digital
samples, 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 analog-to-digital noise is caused by quantiza-
tion error only and results directly from the ADC’s reso-
lution (N bits):
SNR (max) = (6.02 · N + 1.76) dB
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.
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 quantization noise only. ENOB
is computed from a curve fit referenced to the theoreti-
cal full-scale range.
Signal-to-Noise Plus Distortion
Signal-to-noise plus distortion (SINAD) is computed
from the ENOB as follows:
SINAD = (6.02 · ENOB) + 1.76
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 amplitudes of the 2nd- through 5th-order
harmonics.
Spurious-Free Dynamic Range
Spurious-free dynamic range (SFDR) is the ratio,
expressed in decibels, of the RMS amplitude of the fun-
damental (maximum signal component) to the RMS
value of the next-largest spurious component, exclud-
ing DC offset.
Intermodulation Distortion
The two-tone intermodulation distortion (IMD) is the
ratio, expressed in decibels, of either input tone to the
worst 3rd-order (or higher) intermodulation products.
The input tone levels are at -7dB full scale.
THD 20 log V V V V / V
2
2
3
2
4
2
5
2
1
= + + +
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Chip Information
TRANSISTOR COUNT: 20,486
SUBSTRATE CONNECTED TO V EE