AD8002ARMZ(2015) View Datasheet(PDF) - Analog Devices
Part Name
Description
Manufacturer
AD8002ARMZ Datasheet PDF : 21 Pages
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AD8002
Data Sheet
DRIVING ADCs
The AD8002 is well suited for driving high speed analog-to-
digital converters, such as the AD9058. The AD9058 is a dual,
8-bit, 50 MSPS ADC. In Figure 55, the AD8002 drives the
inputs of the AD9058, which are configured for 0 V to 2 V
ranges. Bipolar input signals are buffered, amplified (−2×), and
offset (by 1.0 V) into the proper input range of the ADC. Using
the internal 2 V reference of the AD9058 connected to both
ADCs (as shown in Figure 55) reduces the number of external
components required to create a complete data acquisition
system. The 20 Ω resistors in series with the ADC inputs help
the ADCs drive the 10 pF ADC input capacitance. The AD8002
adds only 100 mW to the power consumption, while not
limiting the performance of the circuit.
SINGLE-ENDED-TO-DIFFERENTIAL DRIVER USING
AN AD8002
The two halves of an AD8002 can be configured to create a
single-ended-to-differential high speed driver with a −3 dB
bandwidth in excess of 200 MHz, as shown in Figure 54.
Although the individual op amps are each current feedback op
amps, the overall architecture yields a circuit with attributes
normally associated with voltage feedback amplifiers, yet offers
the speed advantages inherent in current feedback amplifiers. In
addition, the gain of the circuit can be changed by varying a
single resistor, RF, which is often not possible in a dual op amp
differential driver.
CC = 0.5pF TO 1.5pF
RG
RF 511Ω
511Ω
VIN
OP AMP 1
1/2
AD8002
50Ω
OUTPUT 1
RA
511Ω
RB
511Ω
RA
511Ω
RB
511Ω
1/2
50Ω
AD8002
OP AMP 2
Figure 54. Differential Line Driver
OUTPUT 2
ANALOG
IN A
±0.5V
274Ω
1.1kΩ
–2V
0.1µF
1.1kΩ
ANALOG
IN B
±0.5V
274Ω
549Ω
1/2
50Ω AD8002
AD8597
20kΩ
549Ω
1/2
50Ω AD8002
RZ1, RZ2 = 2,000Ω SIP (8-PKG)
ENCODE
1kΩ
74ACT04
10
36
50Ω
ENCODE
8
–VREF
38
–VREF
ENCODE
5, 9, 22,
+VS 24, 37, 41
+5V
0.1µF
20Ω
20kΩ
0.1µF
20Ω
0.1µF
6 AIN
2
+VINT
3
+VREF
43
+VREF
18
D0 (LSB) 17
16
15
14
13
12
D7 (MSB) 11
AD9058
(J-LEAD)
40
AIN
1
COMP
D0 (LSB)
D7 (MSB)
–VS
28
29
30
31
32
33
34
35
7, 20,
26, 39
4,19, 21 25, 27, 42
0.1µF
RZ1
RZ2
–5V
1N4001
10pF
8
8
CLOCK
Figure 55. AD8002 Driving a Dual ADC
Rev. E | Page 16 of 21
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