AD9122 Analog Devices, AD9122 Datasheet - Page 59

• Manufacturer Part Number: AD9122
• Manufacturer: Analog Devices

Specifications of AD9122

• Resolution (bits): 16bit
• Dac Update Rate: 1.23GSPS
• Dac Settling Time: n/a
• Max Pos Supply (v): +3.47V
• Single-supply: No
• Dac Type: Current Out
• Dac Input Format: LVDS,Par

EXAMPLE START-UP ROUTINE
To ensure reliable start-up of the AD9122, certain sequences
should be followed. This section shows an example start-up
routine. This example uses the configuration described in the
Device Configuration section.
DEVICE CONFIGURATION
The following device configuration is used for this example:
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DERIVED PLL SETTINGS
The following PLL settings can be derived from the device
configuration:
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DERIVED NCO SETTINGS
The following NCO settings can be derived from the device
configuration:
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START-UP SEQUENCE
The following sequence configures the power clock and register
write sequencing for reliable device start-up in PLL ON mode:
Power up Device (no specific power supply
sequence is required)
Apply stable REFCLK input signal.
Apply stable DCI input signal.
Issue H/W RESET (Optional).
f
Interpolation is 4×, using HB1 = 10 and HB2 = 010010
Input data is baseband data
f
f
PLL is enabled
Fine NCO is enabled
Inverse sinc filter is enabled
Synchronization is enabled
Silicon revision is R2
f
f
N1 = f
N2 = f
f
f
FTW = 17.12/(2 × 122.8) × 2
DATA
OUT
REFCLK
DACCLK
VCO
NCO
CARRIER
= 140 MHz
= 4 × f
= 2 × f
= 122.88 MSPS
DACCLK
VCO
= 122.88 MHz
= f
= f
/f
DATA
OUT
DACCLK
DACCLK
DATA
/f
REFCLK
− f
× interpolation = 491.52 MHz
MODHB1
= 1966.08 MHz (1 GHz < f
= 4
= 4
= 140 − 122.88 = 17.12 MHz
32
= 0x11D55555
VCO
< 2 GHz)
Rev. B | Page 59 of 60
Device Configuration Register Write Sequence:
0x00
0x00
/* Start PLL */
0x0D
0x0A
0x0A
/* Verify PLL is Locked */
Read 0x0E
/* Configure Interpolation Filters */
0x1B
0x1C
0x1D
/* Configure NCO */
0x1E
0x30
0x31
0x32
0x33
/* Update Frequency Tuning Word */
0x36
0x36
/* Choose Data Rate Mode */
0x10
/* Issue Software FIFO Reset */
0x17
0x18
/* Verify FIFO Reset */
Read 0x18
0x18
Read 0x19
0x20
0x00
0xD9
0xC0
0x80
0x84
0x04
0x24
0x01
0x55
0x55
0xD5
0x11
0x01
0x00
0x48
0x04
0x02
0x00
/* Issue Software Reset */
/* Expect bit 7 = 1 */
/* Expect 0x07 */
/* Expect 0x1F or 0x0F or 0x07 */
AD9122