AD9467

Data Sheet

Rev. D | Page 20 of 32

AD9467BCPZ-200 buffer current settings:

•

DC to 150 MHz at 80% (default setting)

•

150 MHz to 250 MHz at 100%

•

250 MHz and higher at 160%

80

82

84

86

88

90

92

94

96

98

100

ANALOG INPUT FREQUENCY (MHz)

80%

100%

160%

0

50

100

150

200

250

300

Figure 50. Buffer Current Sweeps, 2.5 V p-p, AD9467-200

Note that for sample rates less than 150 MSPS and analog inputs

less than 100 MHz, it is recommended to set the buffer current

to 0%. Depending on the input network design and frequency

band of interest, the optimum buffer current settings may be

slightly different than the input network recommendations shown

in Figure 53 and Figure 54.

Differential Input Configurations

There are several ways to drive the AD9467, either actively or

passively; however, optimum performance is achieved by

driving the analog input differentially.

For applications where SNR and SFDR are key parameters,

differential transformer coupling is the recommended input

configuration (see Figure 51 and Figure 52) because the noise

performance of most amplifiers is not adequate to achieve the

true performance of the AD9467.

Regardless of the configuration, the value of the shunt capacitor, C,

is dependent on the input frequency and may need to be reduced

or removed (see Figure 51, Figure 52, and Figure 53)

Using the ADL5562 or ADL5201 differential drivers to drive the

AD9467 provides an excellent and flexible gain option to interface

to the ADC (see Figure 54 and Figure 56) for both baseband and

high IF applications. Using an amplifier also provides better

isolation from the preceding stages as well as better pass-band

flatness. Performance plots of these amplifiers can also be seen

in Figure 55 and Figure 57.

When using any dc-coupled amplifier, the user has the option to

disconnect the input common-mode voltage buffer from the analog

inputs. This allows the common-mode output pin of the amplifier

to set this voltage between the interface of the two devices. Other-

wise, use an ac coupling capacitor in series on each of the analog

input as shown in Figure 54 for IF applications that do not require

dc coupling. See the Memory Map section for more details.

AIN+

AIN–

3.5pF

530Ω

ADC

INTERNAL

INPUT Z

AD9467

4.7pF

24Ω

24Ω

0.1µF

0.1µF

0.1µF

0.1µF

33Ω

33Ω

SMA

33Ω

33Ω

ADT1-1WT

0.1µF

0.1µF

ADT1-1WT

10nH 0.1µF

INPUT

Z = 50Ω

3.3V

1.8V

16

NOTES

1. ALL CONNECTIONS AND POWER SUPPLY DECOUPLING NOT SHOWN.

Figure 51. Differential Transformer-Coupled Configuration for Baseband Applications up to 150 MHz

AIN+

AIN–

3.5pF

530Ω

ADC

INTERNAL

INPUT Z

AD9467

1.8pF

20Ω

20Ω

0.1µF

0.1µF

0.1µF

0.1µF

33Ω

33Ω

SMA

15Ω

15Ω

ADT1-1WT

0.1µF

0.1µF

ADT1-1WT

10nH 0.1µF

INPUT

Z = 50Ω

3.3V

1.8V

16

NOTES

1. ALL CONNECTIONS AND POWER SUPPLY DECOUPLING NOT SHOWN.

Figure 52. Differential Transformer-Coupled Configuration for IF Applications from 150 MHz to 300 MHz

1

2

3

4

5

6

7

8

ANAREN

BD0205F5050A00

C3

0.1μF

C2

0.1μF

C1

0.1μF

ANALOG

IN

R2

33Ω

R1

33Ω

R8

15Ω

R7

15Ω

R6

15Ω

R5

15Ω

R3

50Ω

R4

50Ω

C6

8.2pF

C5

8.2pF

AIN–

AIN+

AD9467

3.3V

1.8V

16

NOTES

1. ALL CONNECTIONS AND POWER SUPPLY DECOUPLING NOT SHOWN.

Figure 53. Wideband Balun-Coupled Configuration for IF Applications Up Greater Than 100 MHz