CN-0205 Datasheet, PDF (4/9 Pages) Analog Devices – Interfacing the ADL5375 I/Q Modulator to the AD9122 Dual Channel, 1.2 GSPS High Speed DAC

CN-0205
1.0
0
–1.0
–2.0
–3.0
–4.0
–5.0
–6.0
1M
10M
100M
1G
BB FREQUENCY (Hz)
Figure 6. Baseband (BB) Frequency Response of ADL5375-05
Circuit Note
0
4.0
MAGNITUDE
3.5
–5
3.0
–10
2.5
2.0
–15
1.5
GROUP DELAY
1.0
–20
0.5
–25
1
10
100
FREQUENCY (MHz)
0
500
Figure 8 . Frequency Response for DAC Modulator Interface with 300 MHz
Fifth-Order Butterworth Filter (Simulated)
0
–10
AD9122
IOUT1P
67
RBIP
50Ω
RBIN
66 ^50Ω
IOUT1N
C2PI
22pF
L1PI
33nH
C1I
3.6pF
L1NI
33nH
C2NI
22pF
L2PI
33nH
C3I
6pF
L2NI
33nH
C4PI
3pF
ADL5375-05
21
IBBP
RSLI
100Ω
22
IBBN
C4NI
3pF
IOUT2N
59
RBQN
50Ω
IOUT2P
RBQP
58 ^50Ω
C2NQ
22pF
L1NQ
33nH
C1Q
3.6pF
L1PQ
33nH
C2PQ
22pF
L2NQ
33nH
C3Q
6pF
L2PQ
33nH
C4NQ
3pF
9
QBBN
RSLQ
100Ω
10
QBBP
C4PQ
3pF
Figure 7. Recommended DAC Modulator Interface topology with Fc =300
MHz Fifth-Order, Butterworth Filter
–20
–30
–40
0
100
200
300
400
500
FREQUENCY (MHz)
Figure 9. Measured Frequency Response for DAC Modulator Interface with
300 MHz Fifth-Order Butterworth Filter
0
–10
–20
–30
–40
NO FILTER
–50
–60
–70
–80
–90
–100
WITH FILTER
–110
–120
300
400
500
600
700
800
900 1000
COMMON MODE FREQUENCY (MHz)
Figure10. Measured Common-Mode Rejection Performance at ADL5375-05
RF output with Filter and without Filter
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