Analog Devices AD9854 User Manual

AD9854
Rev. E | Page 17 of 52
VCO
LOOP
FILTER
PHASE
COMPARATOR
REFERENCE
CLOCK
FILTER
AD9854
DDS
TUNING
WORD
REF CLK IN
RF
FREQUENCY
OUT
DAC OUT
PROGRAMMABLE
DIVIDE-BY-N FUNCTION
(WHERE N = 2
48
/TUNING WORD)
00636-029
Figure 29. Programmable Fractional Divide-by-N Synthesizer
TUNING
WORD
VCO
LOOP
FILTER
PHASE
COMPARATOR
REF
CLOCK
RF
FREQUENCY
OUT
FILTER
AD9854
DDS
DIVIDE-BY-N
00636-030
Figure 30. Agile High Frequency Synthesizer
PHASE
SPLITTER
Σ
0.8 TO
2.5GHz
AD9854
QUADRATURE
DDS
DDS – LO
LO DDS
+LO
36dB
TYPICAL
SSB
REJECTION
50Ω
V
OUT
AD8346 QUADR ATURE
MODULATOR
90
COSINE (DC TO 70MHz)
SINE (DC TO 70MHz)
LO
LO
0
0
0636-031
NOTES
1. FLIP DDS QUADRATURE SIGNALS TO SELECT ALTERNATE SIDEBAND. ADJUST DDS
SINE OR COSINE SIGNAL AMPLITUDE FOR GREATEST SIDEBAND SUPPRESSION.
DDS DAC OUTPUTS MUST BE LOW-PASS FILTERED PRIOR TO USE WITH THE AD8346.
Figure 31. Single Sideband Upconversion
REFERENCE
CLOCK
50Ω
1:1 TRANSFORMER
(Mini-Circuits
®
T1-1T)
FILTER
50Ω
DIFFERENTI
A
L
TRANSFORMER-COUPLED
OUTPUT
AD9854
DDS
I
OUT
I
OUT
0
0636-032
Figure 32. Differential Output Connection for Reduction of Common-Mode Signals

Analog Devices AD9854 Specifications

General

Brand	Analog Devices
Model	AD9854
Category	Synthesizer
Language	English