AD9136-EBZ datasheet(76/117 Pages) AD

76 / 117 page

AD9135/AD9136

Data Sheet

Rev. C | Page 76 of 117

Self Calibration

The AD9135/AD9136 have a self calibration feature that

improves the DAC dc and ac linearity in zero or low IF

applications. The performance improvement includes the

INL/DNL, second and fourth harmonic distortions (HD2 and

HD4), and second-order intermodulation distortion (IMD2) of

the device. Figure 85 and Figure 86 show the typical DAC INL

and DNL before and after the calibration. Figure 87 and Figure 88

show the calibration effect on the HD2, HD4, and IMD2

performance. The improvement from calibration decreases with

the DAC output frequency. For improvement in HD2 and HD4,

it is recommended to run the calibration routine when the

desired output frequency is below 100 MHz. For improvement

in IMD2, it is recommended to run the routine when the desired

output frequency is below 200 MHz. A single run of the routine is

sufficient to obtain the desired performance for both ac and dc

performance.

Figure 85. Pre-Calibration and Post-Calibration, INL

Figure 86. Pre-Calibration and Post-Calibration, DNL

Figure 87. Pre-Calibration and Post-Calibration, HD2 and HD4

Figure 88. Pre-Calibration and Post-Calibration, IMD2

To calibrate, follow the routine in Table 75.

Table 75. Device Self Calibration Procedure

Addr.

Bit

SPI Data

Byte

Description

0x0E7

[7:0]

0x38

Use highest comparator speed

and set calibration clock divider

0x0E8

Select DACs to calibrate

Set this bit to 0

0b0 or 0b1

1 if DAC1 is enabled

Set this bit to 0

0b0 or 0b1

1 if DAC0 is enabled

0x0ED

[7:0]

0xA2

Configure initial value

0x0E9

[7:0]

0x01

Enable calibration

0x0E9

[7:0]

0x03

Start calibration

0x0E7

[7:0]

0x30

Disable calibration clock

For each DAC that is calibrated, verify the calibration status

by writing a 1 in the corresponding bit of CAL_PAGE

(Register 0x0E8) and reading Register 0x0E9. If the calibration

completed correctly, CAL_FIN (Register 0x0E9[7]) = 1 to

indicate that calibration is complete, and Register 0x0E9[6:4] = 0

to indicate that no errors have occurred.

–4

–3

–2

–1

70k

60k

50k

40k

30k

20k

10k

DAC GAIN CODE

CALIBRATION OFF

CALIBRATION ON

–2

–1

70k

60k

50k

40k

30k

20k

10k

DAC GAIN CODE

CALIBRATION OFF

CALIBRATION ON

–40

–100

–90

–80

–70

–60

–50

300

250

200

150

100

fOUT (MHz)

CALIBRATION OFF

CALIBRATION ON

SECOND HARMONIC

FOURTH HARMONIC

–60

–65

–70

–75

–80

–85

–90

–95

–100

300

250

200

150

100

fOUT (MHz)

CALIBRATION OFF

CALIBRATION ON

AD9136-EBZ Datasheet(PDF) 76 Page - Analog Devices

AD9136-EBZ Datasheet(HTML) 76 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL