ADL5534

Data Sheet

Rev. B | Page 12 of 16

470nH

470nH

10nF

1nF

1µF

VPOS

GND

10nF

1µF

1nF

VPOS1

GND1

NC

NC

NC

NC

NC

NC

Z1

ADL5534

NC

9

12

4

10

2

11

3

1

RFIN

10nF

AD9640

49.9

Ω

49.9

Ω

120nH

33

Ω

120nH

100pF

120nH

33

Ω

120nH

100pF

16pF

4.7pF

CML

Figure 19. Narrow-Band IF Sampling Solution for Unbuffered ADC

ADC DRIVING APPLICATION

The ADL5534 is a high linearity, fixed gain IF amplifier suitable

for use as an ADC driver. The ADL5534 has a differential input

and output impedance of 100 Ω. A flux-coupled RF transformer

with a 2:1 impedance ratio was used to perform the single-ended-

to-differential conversion at the input of the ADL5534. The

interface between the ADL5534 and the AD9640 is a third-

order low pass filter presenting a 100 Ω differential impedance

to the source and load. The ADL5534 must be ac-coupled to

prevent dc bias from entering the inputs of the ADC. Capacitors

of 100 pF were chosen to reduce any low frequency noise coming

from the ADL5534 and provide dc blocking. The measured

results for this interface shows 0.5 dB insertion loss for a 20 MHz

bandwidth centered around 92 MHz. The wideband response for

the interface is shown in Figure 20. The single-tone results in

Figure 21 show an SNR of 69.3 dB and an SFDR of 82 dBc. The

two-tone results in Figure 22 show an IMD3 of −80.5 dBc and

an SFDR of 78 dBc.

FREQUENCY (MHz)

–45

–40

–35

–30

–25

–20

–15

–10

–5

0

5

50

100

150

200

250

300

350

400

Figure 20. Measured Frequency Response of ADC interface

in Figure 19

FREQUENCY (MHz)

SNR = 69.334dBc

SFDR = 82.267dBc

NOISE FLOOR = –109.519dB

FUND = –1.05dBFs

SECOND = –82.262dBc

THIRD = –88.688dBc

6

0

12

18

24

30

36

42

48

54

60

0

–15

–30

–45

–60

–75

–90

–105

–120

–135

Figure 21. Measured Single-Tone Performance of the Circuit in Figure 19

FREQUENCY (MHz)

SFDR = 78.267dBc

NOISE FLOOR = –110.131dB

FUND 1 = –7.181dBFs

FUND 2 = –7.191dBFs

IMD (2F1 – F2) = –80.538dBc

IMD (2F2 – F1) = –82.086dBc

6

0

12

18

24

30

36

42

48

54

60

0

–15

–30

–45

–60

–75

–90

–105

–120

–135

Figure 22. Measured Two-Tone Performance of the Circuit in Figure 19