AD9767
Figure 41 shows the AD9767, when used with the AD8346,
reconstructing a wideband CDMA signal at 2.4 GHz. The
baseband signal is being sampled at 65 MSPS and has a chip
rate of 8M chips.
โ30
โ40
โ50
โ60 ==
โ70
โ80
โ90
โ100
โ110
c11
c11
โ120
C0
โ130
CENTER 2.4GHz
cu1
C0
3MHz
FREQUENCY
cu1
SPAN 30MHz
Figure 41. CDMA Signal, 8 M Chips Sampled at 65 MSPS,
Recreated at 2.4 GHz Adjacent Channel Power > 60 dBm
Figure 42 shows an example of the AD9767 used in a W-CDMA
transmitter application using the AD6122 CDMA 3 V IF sub-
system. The AD6122 has functions, such as external gain con-
trol and low distortion characteristics, needed for the superior
Adjacent Channel Power (ACP) requirements of W-CDMA.
3V
DVDD AVDD
CLK1
RSET1
2kโ
AD9767
(โI DACโ)
FSADJ1
I DATA
INPUT
INPUT
LATCHES
U1
DAC
LATCHES
DAC
IOUTA
IOUTB
50โ
500โ
500โ
50โ
500โ
500โ
IIPP
IIPN
AD6122
WRT1
WRT2
500โ
500โ
LOIPP
LOIPN
ุ2
PHASE
SPLITTER
Q DATA
INPUT
RSET2
1.9kโ
RCAL
220โ
INPUT
LATCHES
(โQ DACโ)
FSADJ2
REFIO
U2
DAC
LATCHES
DAC
QOUTA
QOUTB
SLEEP
ACOM DCOM
CLK2
0.1โฎF
50โ
500โ
500โ
50โ
GAIN
CONTROL
IIQP
MODOPP
IIQN
MODOPN
TEMPERATURE
COMPENSATION
VCC
VCC
REFIN
VGAIN
GAIN
CONTROL
SCALE
FACTOR
TXOPP
TXOPN
Figure 42. CDMA Transmit Application Using AD9767 and AD6122
REV. B
โ17โ