AD9853 Analog Devices, AD9853 Datasheet - Page 21

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

REV. C
SYSuncomp(f)
SYSuncomp(f)
SYScomp(f)
SYScomp(f)
FIR(f)
FIR(f)
GLOBAL DECLARATIONS
–10
–20
–40
–60
–22
–34
0
2
FUNCTIONS:
InRange (x,a,b)
SRRC(f)
H(f,R)
z(f)
INT(x)
dB(x)
CONSTANTS:
0
0
BW
TAPS
SCALE
FreqScale
PROC_GAIN
N
M
0.5
0.9
4
1
e
0.5 (1+ )
2
if (| x | = 0, –200, 20 log (| x |))
floor(x + 0.5)
j
41
R M – 1
. .
.
k = 0
511
passband
.
stopband
1 if InRange (f, 0, stopband)
0 otherwise
f
4
RESPONSE OF NORMAL SRRC, NORMAL SRRC + CIC, AND COMPENSATED SRRC + CIC
if InRange (f, 0, passband)
cos
0.2
1
z
(x
0.1
R
f
4 .
–k
a) . (x
...EXCESS BANDWIDTH FACTOR FOR SRRC FREQUENCY RESPONSE
...PORTION OF SRRC BANDWIDTH OVER WHICH APPLY CIC CORRECTION (0< <= 1)
...BANDWIDTH OF SRRC FILTER (RELATIVE TO SYMBOLRATE)
...NUMBER OF FIR PULSE SHAPING FILTER TAPS
...SETS MAX VALUE OF FIR PULSE SHAPING FILTER BASED ON FINITE WORD SIZE
...UPSAMPLING RATIO OF FIR PULSE SHAPING FILTER (RELATIVE TO THE SYMBOL RATE)
...PROCESSING GAIN OF CIC FILTERS (USED TO CORRELATE RESULTS WITH AD9853 EVAL. BD.)
...NUMBER OF COMB/INTEGRATOR STAGES IN CIC FILTER
...UNIT DELAYS PER STAGE OF CIC FILTER
0.5 (1 + )
0.5 (1 – )
N
.
.
.
(2 f +
.
0.4
b)
.
Figure 35. MathCad Simulation (Continued)
– 1) if InRange (f, passband, stopband)
0.2
...CIC FILTER TIME INDEX FREQUENCY RESPONSE FUNCTION
...RETURNS 1 IF a<= x <= b, 0 OTHERWISE
...RETURNS NEAREST INTEGER TO x
...RATIO TO DECIBEL CONVERSION FUNCTION
...Z TRANSFORM
0.6
FREQUENCY SCALED TO SYMBOL RATE
FREQUENCY SCALED TO SYMBOL RATE
0.3
0.8
PASSBAND DETAIL
FREQUENCY SCALE – f
FREQUENCY SCALE – f
–21–
1.0
0.4
...SRRC FREQUENCY RESPONSE FUNCTION
(f IS RELATIVE TO THE SYMBOL RATE)
1.2
0.5
1.4
0.6
1.6
1.8
AD9853
0.7
2.0