Rainbow Electronics MAX1211 - Manual (Page 29)

MAX1211
65Msps, 12-Bit, IF Sampling ADC
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Signal-to-Noise Plus Distortion (SINAD)
SINAD is computed by taking the ratio of the RMS sig-
nal to the RMS noise plus distortion. RMS noise plus
distortion includes all spectral components to the
Nyquist frequency, excluding the fundamental and the
DC offset.
Effective Number of Bits (ENOB)
ENOB specifies the dynamic performance of an ADC at a
specific input frequency and sampling rate. An ideal
ADC’s error consists of quantization noise only. ENOB for
a full-scale sinusoidal input waveform is computed from:
Total Harmonic Distortion (THD)
THD is the ratio of the RMS sum of the first six harmon-
ics of the input signal to the fundamental itself. This is
expressed as:
where V 1 is the fundamental amplitude, and V 2 through
V 7 are the amplitudes of the 2nd- through 7th-order
harmonics (HD2–HD7).
Spurious-Free Dynamic Range (SFDR)
SFDR is the ratio expressed in decibels of the RMS
amplitude of the fundamental (maximum signal compo-
nent) to the RMS value of the next-largest spurious
component, excluding DC offset.
3rd-Order Intermodulation (IM3)
IM3 is the total power of the 3rd-order intermodulation
products to the Nyquist frequency relative to the total
input power of the two input tones f1 and f2. The indi-
vidual input tone levels are at -7dBFS. The 3rd-order
intermodulation products are 2 x f1 - f2, 2 x f2 - f1, 2 x
f1 + f2, and 2 x f2 + f1.
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: 18,700
PROCESS: CMOS
THD
V V V V V V
V
= ×
+ + + + +
⎛
⎝
⎜
⎜
⎞
⎠
⎟
⎟
20
2
2
3
2
4
2
5
2
6
2
7
2
1
log
ENOB
SINAD
=
− ⎛
⎝⎜ ⎞
⎠⎟ 1 76
6 02
.
.