AD6622AS Analog Devices Inc, AD6622AS Datasheet - Page 27

• Manufacturer Part Number: AD6622AS
• Manufacturer: Analog Devices Inc

Specifications of AD6622AS

• Lead Free Status / RoHS Status: Not Compliant

Driving Multiple TSP Serial Ports
When properly configured, the AD6622 will drive each SDFS
out of phase. Each new piece of data should be driven only into
the TSP that pulses its SDFS pin at that time.
In the UMTS example, L = 64 and N
need only accept every 4th input sample. Each serial port is
shifting at peak capacity, so sample 1, 2, and 3 begin shifting
into Serial Ports B, C, and D before Sample 0 is completed into
Serial Port A.
MCPS
4.096
32
SDFSA
SDFSB
SDFSC
SDFSD
1.0
0.5
0
0
MCPS
MCPS
MCPS
MCPS
1.024
1.024
1.024
1.024
0
32
32
32
32
COMPLEX SIGNAL 32 BITS (16 I, 16 Q)
REAL OR IMAGINARY SIGNAL
5
1
FILTER
FILTER
FILTER
FILTER
COEF
COEF
COEF
COEF
RAM
RAM
RAM
RAM
COEF – J
8.196MSPS 65.536MSPS
8.196MSPS 65.536MSPS
8.196MSPS 65.536MSPS
8.196MSPS 65.536MSPS
10
2
Q
Q
Q
Q
I
I
I
I
CIC
AD6622
CIC
CIC
CIC
3
15
4
TSP
NCO
NCO
NCO
NCO
20
= 4, so each serial port
5
25
6
65.536
MSPS
30
7
DAC
THERMAL MANAGEMENT
The power dissipation of the AD6622 is primarily determined
by three factors: the clock rate, the number of channels active,
and the distribution of interpolation rates. The faster the clock
rate the more power dissipated by the CMOS structures of
the AD6622; the more channels active, the higher the overall
power of the chip. Low interpolation rates in the CIC stages
(CIC5, CIC2) results in higher power dissipation. All these factors
should be analyzed as each application has different thermal
requirements.
The AD6622 128-lead MQFP is specially designed to provide
excellent thermal performance. To achieve the best performance,
the power and ground leads should be connected directly to
planes on the PC board. This provides the best thermal transfer
from the AD6622 to the PC board.
–100
–110
–120
–100
–10
–20
–30
–40
–50
–60
–70
–80
–90
–10
–20
–30
–40
–50
–60
–70
–80
–90
10
0
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
0
dB(AD6624(f))
SPEC( f )
1000
2000
RAM COEFFICIENT FILTER
3000
4000
MHz
kHz
f
4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0
5000
dB
6000
(
LEVEL
H
CIC
AD6622
7000
(f)
5
)
8000