ADL5961ACCZ-R2 datasheet(28/34 Pages) AD

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Data Sheet

ADL5961

APPLICATIONS INFORMATION

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Rev. 0 | 28 of 34

Multiply by 2 Mode (LOMODE = 2)

The LO signal is passed through a frequency doubler, a program-

mable band-pass filter, and an offset mixer to the downconversion

mixers. The band-pass filter suppresses the subharmonics in the

doubler output signal and can be tuned by programming the CT2

bits in Register 0x21, Bits[4:0]. Table 8 lists the recommended

setting for different 2× fLO ranges. All CT2 settings are valid. For

CT2 settings not shown in Table 8, for example CT2 = 2, CT2 = 5,

…, CT2 = 30, the minimum and maximum 2× fLO can be linearly

interpolated based on the table entries shown in Table 8. The

multiply by 2 mode can be used as a standalone or in combination

with the offset frequency interface.

Table 8. Recommended CT2 Band-Pass Filter Settings for LOMODE = 2

CT2

Minimum 2× fLO (GHz)

Maximum 2× fLO (GHz)

Multiply by 4 Mode (LOMODE = 3)

The LO signal is passed first through a frequency doubler, followed

by the band-pass filter tuned through the CT2 bits (Register 0x21,

Bits[4:0]), through a second frequency doubler, and followed by

a second band-pass filter tuned through the CT4 bits in Register

0x22, Bits[3:0]. The signal is then passed through the offset mixer

to the downconversion mixers. Table 9 lists the recommended

setting for different 4× fLO ranges; however, this list is not exhaus-

tive. Other valid combinations exist that result in frequency ranges

partially or entirely overlapping with the recommended settings.

This mode can be used as a standalone or in combination with the

offset frequency interface.

Table 9. Recommended CT2/CT4 Band-Pass Filter Settings for LOMODE = 3

CT2

CT4

Minimum 4× fLO (GHz)

Maximum 4× fLO (GHz)

<12

>20

>21

IF SIGNAL PATH CONFIGURATION

The IF signal path following the downconversion mixers can be

configured to optimize the output signal dynamic range and to

achieve optimal interfacing to a wide range of ADCs.

Two cascaded LPFs provide programmable IF bandwidth for sup-

pression of out of band noise and spurious tones. The first filter

provides coarse bandwidth adjustment through the CIF1 bits in

Figure 22.

Table 10. IF −3 dB Bandwidth vs. CIF1 with CIF2 = 0

CIF1

f−3dB (MHz)

126

64.0

41.0

30.1

24.1

19.7

16.7

14.5

13.0

11.6

10.5

9.5

8.8

8.1

7.6

7.0

The second filter provides finely spaced lower bandwidth settings

programmable through the CIF2 bits in Register 0x25, Bits[7:4],

listed in Table 11 and shown in Figure 25. Both output channels are

programmed to the same IF bandwidth.

Table 11. IF −3 dB Bandwidth vs. CIF2 with CIF1 = 0

CIF2

f−3dB (MHz)

126

11.1

5.9

3.8

3.1

2.3

1.6

1.5

1.3

1.2

1.0

0.99

0.86

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