AD9853 Analog Devices, AD9853 Datasheet - Page 6

• Manufacturer Part Number: AD9853
• Description: Programmable Digital OPSK/16-QAM Modulator
• Manufacturer: Analog Devices

AD9853
NOTES
1
2
3
4
5
Register
Address
(Note 1)
00h
01h
02h
03h
04h
05h
06h
11h
12h
13h
14h
15h
16h
19h
1Ah
1Dh
1Eh
1Fh
46h
47h
48h
(Note 7)
49h
(Note 8)
:
The 8-bit Register Address is preceded by an 8-bit Device Address, which is given by
000001XY, where the value of Bits X and Y are determined as follows:
This register must be loaded with a nonzero value even if the RS encoder has been
disabled by setting T = 0 in register 01h.
Unused regions are don’t care bit locations.
If a preamble is not used this register must be initialized to a value of 0 by the user.
Addresses 06h–011h and 1Eh–47h are write only.
:
:
:
:
:
X
0
1
6
5
Voltage Applied to Pin 6
GND
+V
S
D7
MSB
MSB
MSB
MSB
MSB
Modulation Mode
000
011
The MSB of the preamble always resides in D7 of Address 11h and is the first preamble bit to be clocked out of the device during transmission of
a packet. Up to 96 bits of preamble are available as specified in Register 04h. Unused bits are don’t care for L < 96.
MSB
MSB
MSB
MSB
MSB
MSB-2
MSB
MSB-2
MSB
Spectrum
0 = I Cos + Q Sin
1 = I Cos – Q Sin
MSB
2
2
= QPSK , 001
= D16-QAM , 100
0
20
2
= DQPSK, 010
2
= FSK
D6
The Number of Correctable Byte
Lower Eight Bits of Seed Value for 15-Bit Randomizer (Not Used for 6-Bit Randomizer)
Upper Seven Bits of Seed Value for 15-Bit Randomizer
Preamble Length (L) where 0 L 96 Bits (Note 4)
MSB
MSB
MSB-3
MSB-3
Digital Power
Value of K (Message Length in Bytes) for Reed-Solomon Encoder, where 16
Errors (t) for the Reed-Solomon
Encoder, where 0
For t = 0, the RS encoder is
effectively disabled.
– OR –
Seed Value for 6-Bit Randomizer (D1 not used in this case).
Interpolator #1: SCALE
Interpolator #2: SCALE
MSB-1
MSB-1
0 = Normal
1 = Shutdown
The absolute gain, A
Y
0
1
Table II. Control Register Functional Assignment
Desired Register Function
WRITE
READ
2
= 16-QAM
t
V
, of the AD8320 is given by: A
D5
Preamble Data. (Note 5)
Interpolator #1: RATE
Rate Change Factor (R) where 3
Interpolator #2: RATE
Rate Change Factor (R) where 2
Frequency Tuning Word #1
FSK Mode: Specifies the “space” frequency (F0).
All Other Modes: Specifies the carrier frequency.
Frequency Tuning Word #2
FSK Mode: Specifies the “mark” frequency (F1).
(Addresses 1Ah–1Dh are only valid for FSK mode.)
10-Bit FIR End Tap Coefficient, a
< — — — — — — — — — — — — — — Unused Bits — — — — — — — — — — — — — — >
FIR Intermediate Tap Coefficients, a
10-Bit FIR Center Tap Coefficient, a
< — — — — — — — — — — — — — — Unused Bits — — — — — — — — — — — — — — >
6 RefClk
0 = Off
1 = On
AD8320 Cable Driver Gain Control Byte (GCB)
10
10
.
–6–
D4
1 = Sleep
LSB
PLL Mode
0 = Awake
6
7
8
Readback of register 15h results in a value that is 2 the actual programmed value.
Assertion of RESET (Pin 32) sets the contents of this register to 0.
Registers 0h–48h may be written to using a single register address followed by a
This is a design error in the readback function.
contiguous data sequence (see Figure 27). Register 49h, however, must be written to
individually; i.e., a separately addressed 8-bit data sequence.
DATA
V
= 0.316 + 0.077 GCB (where 0
10
10
0
R 31
R 63
1
20
D3
Randomizer
Insertion
0 = After RS
1 = Before RS
LSB
DAC Mode
0 = Awake
1 = Sleep
– a
19
10
10
10
Randomizer Length
D2
K 255
00
01
10
11
LSB
2 Multiplier
0 = OFF
1 = ON
LSB
2
2
2
2
= 6 Bit
= 15 Bit
= Randomizer OFF
= Randomizer OFF
10
(Note 2)
GCB
D1
LSB
LSB
LSB
255
10
)
REV. C
D0
LSB
(Note 3)
LSB
LSB
LSB
LSB
LSB
LSB
0
20