adc12d800rfrb National Semiconductor Corporation, adc12d800rfrb Datasheet - Page 28

• Manufacturer Part Number: adc12d800rfrb
• Description: 12-bit, 1.6/1.0 Gsps Rf Sampling Adc
• Manufacturer: National Semiconductor Corporation

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13.0 Specification Definitions
APERTURE (SAMPLING) DELAY is the amount of delay,
measured from the sampling edge of the CLK input, after
which the signal present at the input pin is sampled inside the
device.
APERTURE JITTER (t
from sample-to-sample. Aperture jitter can be effectively con-
sidered as noise at the input.
CODE ERROR RATE (CER) is the probability of error and is
defined as the probable number of word errors on the ADC
output per unit of time divided by the number of words seen
in that amount of time. A CER of 10
tistical error in one word about every 31.7 years for the
ADC12D800RF.
CLOCK DUTY CYCLE is the ratio of the time that the clock
waveform is at a logic high to the total time of one clock period.
DIFFERENTIAL NON-LINEARITY (DNL) is the measure of
the maximum deviation from the ideal step size of 1 LSB. It is
measured at the relevant sample rate, f
sine wave.
EFFECTIVE NUMBER OF BITS (ENOB, or EFFECTIVE
BITS) is another method of specifying Signal-to-Noise and
Distortion Ratio, or SINAD. ENOB is defined as (SINAD −
1.76) / 6.02 and states that the converter is equivalent to a
perfect ADC of this many (ENOB) number of bits.
GAIN ERROR is the deviation from the ideal slope of the
transfer function. It can be calculated from Offset and Full-
Scale Errors. The Positive Gain Error is the Offset Error minus
the Positive Full-Scale Error. The Negative Gain Error is the
Negative Full-Scale Error minus the Offset Error. The Gain
Error is the Negative Full-Scale Error minus the Positive Full-
Scale Error; it is also equal to the Positive Gain Error plus the
Negative Gain Error.
GAIN FLATNESS is a measure of the variation in gain over
the specified bandwidth. For example, for the AD-
C12D800RF, from D.C. to Fs/2 is to 400 MHz for the Non-
DES Mode and from D.C to Fs/2 is to 800 MHz for the DES
Mode.
INTEGRAL NON-LINEARITY (INL) is a measure of worst
case deviation of the ADC transfer function from an ideal
straight line drawn through the ADC transfer function. The
deviation of any given code from this straight line is measured
from the center of that code value step. The best fit method
is used.
INSERTION LOSS is the loss in power of a signal due to the
insertion of a device, e.g. the ADC12D800/500RF, expressed
in dB.
INTERMODULATION DISTORTION (IMD) is measure of the
near-in 3rd order distortion products (2f
occur when two tones which are close in frequency (f
applied to the ADC input. It is measured from the input tones
power of the higher of the two distortion products (dBFS). The
input tones are typically -7dBFS.
LSB (LEAST SIGNIFICANT BIT) is the bit that has the small-
est value or weight of all bits. This value is
where V
by the FSR input and "N" is the ADC resolution in bits, which
is 10 for the ADC12D800/500RF.
LOW VOLTAGE DIFFERENTIAL SIGNALING (LVDS)
DIFFERENTIAL OUTPUT VOLTAGE (V
times the absolute value of the difference between the V
and V
D
- signals; each signal measured with respect to
FS
is the differential full-scale amplitude V
AJ
) is the variation in aperture delay
V
FS
/ 2
N
-18
corresponds to a sta-
CLK
2
ID
- f
, with f
1
and V
, 2f
1
IN_FSR
- f
IN
OD
2
1
= 1MHz
) is two
) which
, f
as set
2
) are
D
+
28
Ground. V
is V
peak-to-peak.
LVDS OUTPUT OFFSET VOLTAGE (V
between the D+ and D- pins output voltage with respect to
ground; i.e., [(V
MISSING CODES are those output codes that are skipped
and will never appear at the ADC outputs. These codes can-
not be reached with any input value.
MSB (MOST SIGNIFICANT BIT) is the bit that has the largest
value or weight. Its value is one half of full scale.
NEGATIVE FULL-SCALE ERROR (NFSE) is a measure of
how far the first code transition is from the ideal 1/2 LSB above
a differential −V
ADC12D800/500RF the reference voltage is assumed to be
ideal, so this error is a combination of full-scale error and ref-
erence voltage error.
NOISE FLOOR DENSITY is a measure of the power density
of the noise floor, espressed in dBFS/Hz and dBm/Hz. '0
dBFS' is defined as the power of a sinusoid which precisely
uses the full-scale range of the ADC.
NOISE POWER RATIO (NPR) is the ratio of the sum of the
power inside the notched bins to the sum of the power in an
equal number of bins outside the notch, expressed in dB.
OFFSET ERROR (V
scale point is from the ideal zero voltage differential input.
Offset Error = Actual Input causing average of 8k samples to
result in an average code of 2047.5.
OUTPUT DELAY (t
cy) after the rising edge of CLK+ before the data update is
present at the output pins.
OVER-RANGE RECOVERY TIME is the time required after
the differential input voltages goes from ±1.2V to 0V for the
converter to recover and make a conversion with its rated ac-
curacy.
PIPELINE DELAY (LATENCY) is the number of input clock
cycles between initiation of conversion and when that data is
presented to the output driver stage. The data lags the con-
version by the Latency plus the t
POSITIVE FULL-SCALE ERROR (PFSE) is a measure of
how far the last code transition is from the ideal 1-1/2 LSB
below a differential +V
reference voltage is assumed to be ideal, so this error is a
combination of full-scale error and reference voltage error.
SIGNAL TO NOISE RATIO (SNR) is the ratio, expressed in
dB, of the rms value of the fundamental for a single-tone to
the rms value of the sum of all other spectral components
below one-half the sampling frequency, not including har-
monics or DC.
OD,P-P
= 2*(V
FIGURE 2. LVDS Output Signal Levels
OD
peak is V
D
D
+ - V
+) +( V
IN
OD
/2 with the FSR pin low. For the
D
OFF
OD,P
-); for this product, the V
) is the time delay (in addition to Laten-
IN
D
) is a measure of how far the mid-
/2. For the ADC12D800/500RF the
-)]/2. See
= (V
D
+ - V
OD
Figure
.
D
-) and V
OS
2.
) is the midpoint
OD
30128646
OD
peak-to-peak
is measured