Typical Applications - Analog Devices AD9854 User Manual

AD9854

TYPICAL APPLICATIONS

Rx
RF IN
RF/IF
AD9854
INPUT
REFCLK
Figure 25. Quadrature Downconversion
I BASEBAND
AD9854
REFCLK
Q BASEBAND
Figure 26. Direct Conversion Quadrature Upconverter
I
I/Q MIXER
AND
LOW-PASS
Q
FILTER
VCA
ADC CLOCK FREQUENCY
LOCKED TO Tx CHIP/
SYMBOL/PN RATE
REFERENCE
CLOCK
Figure 27. Chip Rate Generator in Spread Spectrum Application
I
OUT
AD9854
50Ω
AD9854
SPECTRUM
FUNDAMENTAL
F – F F + F
C O C O
IMAGE IMAGE
F
CLK
Figure 28. Using an Aliased Image to Generate a High Frequency
Rev. E | Page 16 of 52
I BASEBAND
LPF
COS
LPF
CHANNEL
SELECT
FILTERS
LPF
SIN
Q BASEBAND
LPF
COS
LPF
RF OUTPUT
LPF
SIN
8
DUAL
DIGITAL
8-/10-BIT
DEMODULATOR
8
ADC
ADC ENCODE
AD9854
48
CLOCK
CHIP/SYMBOL/PN
GENERATOR
RATE DATA
BAND-PASS
AMPLIFIER
FILTER
50 Ω
FINAL OUTPUT
SPECTRUM
F + F
C O
IMAGE
BAND-PASS
FILTER
Rx BASEBAND
DIGITAL DATA
OUT
AGC