AD9858

Rev. C | Page 27 of 32

APPLICATIONS INFORMATION

DAC

FILTER

PHASE/

FREQUENCY

DETECTOR

150MHz

DIVIDER

1/2/4

DIVIDER

1/2

ANALOG

MIXER

CHARGE PUMP

0.5mA TO 2mA

(0.5mA STEPS)

LOOP

FILTER

FIXED

LOOP

(LO1)

DDS

1GSPS

FREQUENCY

TUNING WORD

DC TO 400MHz

2GHz

2GHz ±150MHz

AD9858

2GHz

DDS/DAC

CLOCK 1000MHz

fREF

DC TO 150MHz

10

32

FILTER

VCO

Figure 37. DDS Synthesizer Translation Loop Oscillator (Implemented in Translation Loop Evaluation Board)

DAC

FILTER

PHASE/

FREQUENCY

DETECTOR

150MHz

DIVIDER

1/2/4

CHARGE PUMP

0.5mA TO 2mA

(0.5mA STEPS)

LOOP

FILTER

DDS

1GSPS

FREQUENCY

TUNING WORD

DC TO 400MHz

VCO

DDS/DAC CLOCK

AD9858

F = M ×

fREF

fREF

DC TO 150MHz

10

32

DIVIDER

Figure 38. DDS Synthesizer Single-Loop PLL Up-Conversion

DAC

FILTER

PHASE/

FREQUENCY

DETECTOR

150MHz

DDS

1GSPS

DIVIDER

1/2/4

DIVIDER

1/2

CHARGE PUMP

0.5mA TO 2mA

(0.5mA STEPS)

LOOP

FILTER

150MHz

REFERENCE

FREQUENCY

TUNING WORD

150MHz

1000

MHz

VCO

2GHz MAX

AD9858

32

Figure 39. DDS Synthesizer AD9858 as Fractional N Synthesizer (Implemented in Fractional Divide Evaluation Board)