AD9060KZ Analog Devices Inc, AD9060KZ Datasheet - Page 7

• Manufacturer Part Number: AD9060KZ
• Description: IC ADC 10BIT 75MSPS 68-CLCC
• Manufacturer: Analog Devices Inc

Specifications of AD9060KZ

• Number Of Bits: 10
• Sampling Rate (per Second): 75M
• Data Interface: Parallel
• Number Of Converters: 1
• Power Dissipation (max): 3.5W
• Voltage Supply Source: Dual ±
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 68-CLCC

The actual resolution of the converter is limited by the thermal
and quantization noise of the ADC. The low frequency test for
SNR or ENOB is a good measure of the noise of the AD9060.
At this frequency, the static errors in the ADC determine the
useful dynamic range of the ADC.
Although the signal being sampled does not have a significant
slew rate, this does not imply that dynamic performance is not
important. The Transient Response and Overvoltage Recovery Time
specifications ensure that the ADC can track full-scale changes
in the analog input sufficiently fast to capture a valid sample.
Transient Response is the time required for the AD9060 to achieve
full accuracy when a step function is applied. Overvoltage Recovery
Time is the time required for the AD9060 to recover to full accu-
racy after an analog input signal 150% of full scale is reduced to
the full-scale range of the converter.
Professional Video
Digital Signal Processing (DSP) is now common in television
production. Modern studios rely on digitized video to create state-
of-the-art special effects. Video instrumentation also requires high
resolution ADCs for studio quality measurement and frame
storage.
The AD9060 provides sufficient resolution for these demanding
applications. Conversion speed, dynamic performance, and analog
bandwidth are suitable for digitizing both composite and RGB
video sources.
USING THE AD9060
Voltage References
The AD9060 requires the user to provide two voltage references:
+V
internal resistor ladder (nominally 37 Ω) and set the analog input
voltage range of the converter. The voltage references should be
driven from a stable, low impedance source. In addition to these
two references, three evenly spaced taps on the resistor ladder
(1/4
to these quarter points on the resistor ladder will improve the
integral linearity of the converter and improve ac performance
(ac and dc specifications are tested while driving the quarter
points at the indicated levels). The figure below is not intended
to show the transfer characteristic of the ADC but illustrates
how the linearity of the device is affected by the reference voltages
applied to the ladder.
REV. B
ENCODE
REF
REF
+F
–F
S
S
and –V
, 1/2
Figure 1. Imaging Application Using AD9060
REF
REF
, and 3/4
. These two voltages are applied across an
REF
) are available. Providing a reference
A
IN
AD9060
–7–
Resistance between the reference connections and the taps of the
first and last comparators causes offset errors. These errors, called
“top and bottom of the ladder offsets,” can be nulled by using
the voltage sense lines, +V
ence voltages. Current through the sense lines should be limited
to less than 100 µA. Excessive current drawn through the voltage
sense lines will affect the accuracy of the sense line voltage.
Figure 4 shows a reference circuit that nulls out the offset errors
using two op amps and provides appropriate voltage references to
the quarter-point taps. Feedback from the sense lines causes the
op amps to compensate for the offset errors. The two transistors
limit the amount of current drawn directly from the op amps;
resistors at the base connections stabilize their operation. The
10 kΩ resistors (R1–R4) between the voltage sense lines form an
external resistor ladder; the quarter point voltages are taken off
this external ladder and buffered by an op amp. The actual values
of resistors R1–R4 are not critical, but they should match well
and be large enough (≥10 kΩ) to limit the amount of current
drawn from the voltage sense lines.
The select resistors (R
a potentiometer) are chosen to adjust the quarter-point voltage
references but are not necessary if R1–R4 match within 0.05%.
An alternative approach for defining the quarter-point references
of the resistor ladder is to evaluate the integral linearity error of
an individual device and adjust the voltage at the quarter-points
to minimize this error. This may improve the low frequency
ac performance of the converter.
1111111111
1100000000
1000000000
0100000000
0000000000
Figure 2. Effect of Reference Taps on Linearity
–V
SENSE
(NOT TO SCALE)
S
1/4
) shown in the schematic (each pair can be
REF
FLOATING
SENSE
TAPS
and –V
1/2
V
REF
IN
DRIVEN
LINEARITY
TAPS
SENSE
IDEAL
, to adjust the refer-
3/4
AD9060
REF
+V
SENSE