ADC11DV200EB/NOPB National Semiconductor, ADC11DV200EB/NOPB Datasheet - Page 18

• Manufacturer Part Number: ADC11DV200EB/NOPB
• Description: EVAL BOARD FOR ADC11DV200
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of ADC11DV200EB/NOPB

• Number Of Adc's: 2
• Number Of Bits: 11
• Sampling Rate (per Second): 200M
• Data Interface: Parallel
• Inputs Per Adc: 1 Differential
• Input Range: 1.5 Vpp
• Power (typ) @ Conditions: 450mW @ 200MSPS
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: ADC11DV200
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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2.1.2 Driving the Analog Inputs
The V
internal sample-and-hold circuit which consists of an analog
switch followed by a switched-capacitor amplifier.
One short-coming of using a transformer to achieve the sin-
gle-ended to differential conversion is that most RF trans-
formers have poor low frequency performance. A differential
amplifier can be used to drive the analog inputs for low fre-
quency applications. The amplifier must be fast enough to
settle from the charging glitches on the analog input resulting
from the sample-and-hold operation before the clock goes
high and the sample is passed to the ADC core.
2.1.3 Input Common Mode Voltage
The input common mode voltage, V
of 0.8V to 1.0V and be a value such that the peak excursions
of the analog signal do not go more negative than ground or
more positive than the VA supply. It is recommended to use
V
If the ADC11DV200 is operated with V
approximately 1KΩ should be used from the V
ND. This will help maintain stability over the entire tempera-
ture range when using a high supply voltage.
RM
V
V
V
V
(pins 5,11) as the input common mode voltage.
CM
CM
CM
CM
IN
+ and the V
V
− V
− V
V
+ V
+ V
CM
IN
+
REF
REF
REF
REF
/2
/4
/4
/2
IN
− inputs of the ADC11DV200 have an
V
V
V
V
CM
CM
CM
CM
V
V
+ V
+ V
− V
− V
FIGURE 7. High Input Frequency Transformer Drive Circuit
FIGURE 6. Low Input Frequency Transformer Drive Circuit
CM
IN
CM
−
REF
REF
REF
REF
, should be in the range
/2
/4
/4
/2
A
=1.8V, a resistor of
TABLE 2. Input to Output Relationship
RM
pin to AG-
Binary Output
000 0000 0000
010 0000 0000
100 0000 0000
110 0000 0000
111 1111 1111
18
Figure 6 and Figure 7 show examples of single-ended to dif-
ferential conversion circuits. The circuit in Figure 6 works well
for input frequencies up to approximately 70MHz, while the
circuit in Figure 7 works well above 70MHz.
2.2 Reference Pins
The ADC11DV200 is designed to operate with an internal or
external voltage reference. The voltage on the V
lects the source and level of the reference voltage. An internal
0.75 Volt reference is used when a voltage between 1.4 V to
VA is applied to the V
sued when a voltage between 0.2V and AGND is applied to
the V
the V
will improve without a significant degradation in SFDR for
V
be maintained. If using an external reference the V
should be bypassed to ground with a 0.1 µF capacitor close
to the reference input pin.
It is important that all grounds associated with the reference
voltage and the analog input signal make connection to the
ground plane at a single, quiet point to minimize the effects of
noise currents in the ground path.
The Reference Bypass Pins (V
A and B are made available for bypass purposes. These pins
should each be bypassed to AGND with a low ESL (equivalent
REF
=1.0V. SNR will decrease if V
REF
REF
2’s Complement Output
pin. If a voltage between 0.2V and 1.4V is applied to
pin, then that voltage is used for the reference. SNR
100 0000 0000
110 0000 0000
000 0000 0000
010 0000 0000
011 1111 1111
30087582
REF
pin. An internal 0.5 Volt reference is
30087583
RP
, V
REF
RM
, and V
=0.5V, yet linearity will
Negative Full-Scale
Positive Full-Scale
Mid-Scale
RN
) for channels
REF
REF
pin se-
pin