ADL5535 Analog Devices, Inc., ADL5535 Datasheet - Page 12

• Manufacturer Part Number: ADL5535
• Description: 20 Mhz To 1.0 Ghz If Gain Block
• Manufacturer: Analog Devices, Inc.

ADL5535
ADC DRIVING APPLICATION
The ADL5535 is a high linearity, fixed gain IF amplifier suitable
for use as an ADC driver. Figure 22 shows the schematic of the
ADL5535 driving the
(ADC). The ADL5535 has a single-ended input and output imped-
ance of 50 Ω. A 1:1 impedance transformer, along with termination
resistors and series ferrite beads, are used to present a 50 Ω load
for the antialiasing filter interface. The filter interface between the
ADL5535 and the AD9268 is a sixth-order Butterworth low-pass
filter. The interface provides a 50 MHz, 1 dB bandwidth centered
around 175 MHz. Following the sixth-order filter, a shunt LC tank
circuit was inserted to further reduce the low frequency response
of the filter, giving more of a band-pass response to the filter.
The normalized wideband response is shown in Figure 19.
–10
–15
–20
–25
–30
–35
–40
–45
Figure 19. Normalized Response of the ADC Interface Shown
–5
5
0
50Ω
0
50
ADL5535
470nH
100
AD9268
5V
150
FREQUENCY (MHz)
in Figure 22
100pF
16-bit analog-to-digital converter
200
22nH
250
Figure 22. Schematic of the ADL5535 Driving the AD9268 16-Bit ADC
22pF
68nH
300
350
27pF
56nH
400
8pF
Rev. 0 | Page 12 of 16
72nH
8.2pF
MABA-007159-000000
Figure 20. Measured Single-Tone Performance of the Circuit Shown
Figure 21. Measured Two-Tone Performance of the Circuit Shown
–105
–120
–135
–105
–120
–135
–15
–30
–45
–60
–75
–90
–15
–30
–45
–60
–75
–90
1
0
0
0
0
FUNDAMENTAL1 = –7.161dBFS
FUNDAMENTAL2 = –7.116dBFS
IMD (2f1 – f2) = –66.07dBc
IMD (2f2 – f1) = –67.588dBc
NOISE FLOOR = –150.84dBFS/√Hz
f2 – f1
SAMPLE FREQUENCY = 122.88MHz
SNRFS = 75.877dB
INPUT FREQUENCY = 170MHz
FUNDAMENTAL POWER = –1.044dBFS
SECOND HARMONIC POWER = –75.499dBc
THIRD HARMONIC POWER = –80.003dBc
NOISE FLOOR = –153.762dBFS/√Hz
0.1µF
0.1µF
6
6
VCM
VCM
33Ω
33Ω
5
12
12
FERRITE BEAD
10Ω AT 100MHz
FERRITE BEAD
10Ω AT 100MHz
18
18
3
FREQUENCY (MHz)
FREQUENCY (MHz)
in Figure 22
in Figure 22
24
24
2
f1 + f2
30
30
66Ω
36
66Ω
36
6
2f1 – f2
42
42
VIN+A
VIN–A
AD9268
48
48
+
2f2 – f1
54
54
4
60
60