AD9600 Analog Devices, AD9600 Datasheet - Page 24

• Manufacturer Part Number: AD9600
• Description: 10-Bit, 105 MSPS/125 MSPS/150 MSPS, 1.8 V Dual Analog-to-Digital Converter
• Manufacturer: Analog Devices

Specifications of AD9600

• Resolution (bits): 10bit
• # Chan: 2
• Sample Rate: 150MSPS
• Interface: LVDS,Par
• Analog Input Type: Diff-Uni
• Ain Range: (2Vref) p-p,1 V p-p,2 V p-p
• Adc Architecture: Pipelined
• Pkg Type: CSP

AD9600
ADC. The output common-mode voltage of the
easily set with the CML pin of the AD9600 (see Figure 46), and
the driver can be configured in a Sallen-Key filter topology to
band limit the input signal.
For baseband applications where SNR is a key parameter,
differential transformer coupling is the recommended input
configuration. An example is shown in Figure 47. The CML
voltage can be connected to the center tap of the transformer’s
secondary winding to bias the analog input.
The signal characteristics must be considered when selecting
a transformer. Most RF transformers saturate at frequencies
below a few megahertz. Excessive signal power can cause core
saturation, which leads to distortion.
At input frequencies in the second Nyquist zone and above, the
noise performance of most amplifiers is not adequate to achieve
the true SNR performance of the AD9600. For applications where
SNR is a key parameter, differential double-balun coupling is
the recommended input configuration. An example is shown
in Figure 49.
1V p-p
Figure 46. Differential Input Configuration Using the AD8138
Figure 47. Differential Transformer-Coupled Configuration
2V p-p
0.1µF
49.9Ω
49.9Ω
499Ω
523Ω
0.1µF
ANALOG INPUT
ANALOG INPUT
2V p-p
AD8138
499Ω
499Ω
R
R
0.1µF
C
C
R
R
P
D
A
C
0.1µF
0.1µF
VIN+
VIN–
CML
R
AD9600
Figure 50. Differential Input Configuration Using the AD8352
D
Figure 49. Differential Double-Balun Input Configuration
S
0Ω
0Ω
VIN+
VIN–
AD9600
AD8138
AVDD
CML
R
S
G
16
1
2
3
4
5
is
AD8352
P
V
Rev. B | Page 24 of 72
0.1µF
0.1µF
CC
14
8, 13
0.1µF
10
11
25Ω
25Ω
0.1µF
0.1µF
An alternative to using a transformer-coupled input at
frequencies in the second Nyquist zone is to use the AD8352
differential driver. An example is shown in Figure 50. See the
AD8352
In any configuration, the value of the shunt capacitor, C, is
dependent on the input frequency and source impedance and may
need to be reduced or removed. Table 10 lists the recommended
values to set the RC network. However, the actual values are
dependent on the input signal; therefore, Table 10 should only
be used as a starting guide.
Table 10. Example RC Network
Frequency Range (MHz)
0 to 70
70 to 200
200 to 300
>300
Single-Ended Input Configuration
A single-ended input can provide adequate performance in
cost-sensitive applications. In this configuration, SFDR and
distortion performance degrade due to the large input common-
mode swing. If the source impedances on each input are matched,
there should be little effect on SNR performance. Figure 48
details a typical single-ended input configuration.
0.1µF
2V p-p
200Ω
200Ω
0.1µF
R
R
data sheet for more information.
C
10µF
0.1µF
49.9Ω
R
R
Figure 48. Single-Ended Input Configuration
C
VIN+
VIN–
0.1µF
10µF
0.1µF
AD9600
VIN+
VIN–
AVDD
AD9600
R Series (Ω, Each)
33
33
15
15
1kΩ
1kΩ
1kΩ
1kΩ
AVDD
CML
CML
R
R
C
VIN+
VIN–
C Differential (pF)
15
5
5
Open
AD9600
ADC