
AD5930 
THEORY OF OPERATION
The AD5930 is a general-purpose synthesized waveform 
generator capable of providing digitally programmable 
waveform sequences in both the frequency and time domain. 
The device contains embedded digital processing to provide a 
repetitive sweep of a user programmable frequency profile 
allowing enhanced frequency control. Because the device is pre-
programmable, it eliminates continuous write cycles from a 
DSP/μcontroller in generating a particular waveform.  
Rev. 0 | Page 16 of 28 
THE FREQUENCY PROFILE 
The frequency profile is defined by the start frequency (F
START
), 
the frequency increment (Δf) and the number of increments 
per sweep (N
INCR
). The increment interval between frequency 
increments, t
INT
, is either user programmable with the interval 
automatically determined by the device (auto-increment mode), 
or externally controlled via a hardware pin (external increment 
mode). For automatic update, the interval profile can either be 
for a fixed number of clock periods or for a fixed number of 
output waveform cycles. 
In the auto-increment mode, a single pulse at the CTRL pin starts 
and executes the frequency sweep. In the external increment 
mode, the CTRL pin also starts the sweep, but the frequency 
increment interval is determined by the time interval between 
sequential 0/1 transitions on the CTRL pin. Furthermore, the 
CTRL pin can be used to directly control the burst profile, where 
during the input high time, the output waveform is present, and 
during the input low time, the output is reset to midscale. 
The frequency profile can be swept in two different modes: saw 
sweep or triangular (up/down) sweep. 
Saw-Sweep Mode 
In the case of a saw sweep, the AD5930 repeatedly  
sweeps between sweep start to sweep end, that is, from  
F
START
 incrementally to 
F
START
 + N
INCR
 × Δf  
and then returns directly to F
START
 to begin again (see Figure 31). 
This gives a saw-sweep cycle time of 
(N
INCR
 + 1) × t
INT
F
START
F
START
F
START
 + 
F
F
START
 + N
INCR
 × 
F
MIDSCALE
0
Figure 31. Saw-Sweep Profile 
Triangular-Sweep Mode 
In the case of a triangular sweep, the AD5930 repeatedly  
sweeps between sweep start to sweep end, that is, from F
START 
incrementally to  
F
START
 + N
INCR
 × Δf 
and then returns to F
START
 in a decremented manner (see Figure 32).  
The triangular-sweep cycle time is given by  
(1 + (2 × N
INCR
)) × t
INT
F
START
0
F
START
F
START
F
START
 + 
F
F
START
 + 
F
F
START
 + N
INCR
 × 
F
MIDSCALE
Figure 32. Triangular-Sweep Profile 
OUTPUT MODES 
The AD5930 offers two possible output modes: continuous 
output mode and burst output mode. Both of these modes are 
illustrated in Figure 33. 
0
CONTINUOUS
MODE
BURST
MODE
1
2
NUMBER STEP CHANGES
t
INT
T
BURST
Figure 33. Continuous Mode and Burst Mode of the AD5930 
Continuous Output Mode 
In this mode, each frequency of the sweep is available for the 
length of time programmed into the time interval (t
INT
) register. 
This means the frequency swept output signal is continuously 
available, and is therefore phase continuous at all frequency 
increments. 
To set up the AD5930 in continuous mode, the CW/BURST bit 
(D7) in the control register must be set to 0. See the Activating 
and Controlling the Sweep section for more details. 
Burst Output Mode 
In this mode, the AD5930 provides a programmable burst  
of the waveform output for a fixed length of time (T
BURST
)  
within the programmed increment interval (t
INT
). Then for  
the remainder of the t
INT
 interval, the output is reset to mid-
scale and remains there until the next frequency increment.