Rainbow Electronics MAX5184 - Manual (Page 12)

MAX5181/MAX5184
10-Bit, 40MHz, Current/Voltage-Output DACs
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The I/Q reconstruction system is completed by a quad-
rature modulator that combines the reconstructed com-
ponents with in-phase and quadrature carrier
frequencies and then sums both outputs to provide the
QAM signal.
Using the MAX5181/MAX5184 for
Arbitrary Waveform Generation
Designing a traditional arbitrary waveform generator
(AWG) requires five major functional blocks (Figure 8a):
clock generator, counter, waveform memory, DAC for
waveform reconstruction, and output filter. The wave-
form memory contains the sequentially stored digital
replica of the desired analog waveforms. This memory
shares a common clock with the DAC.
For each clock cycle, a counter adds one count to the
address for the waveform memory. The memory then
loads the next value to the DAC, which generates an
analog output voltage corresponding to that data value.
A DAC output filter can either be a simple or complex
lowpass filter, depending on the AWG requirements for
waveform function and frequencies. The main limita-
tions of the AWG’s flexibility are DAC resolution and
dynamic performance, memory length, clock frequen-
cy, and the filter characteristics.
Although the MAX5181/MAX5184 offer high-frequency
operation and excellent dynamics, they are suitable for
0
2
1
4
3
7
6
5
000 010 001 011 100 101 110
AT STEP
011 (1/2 LSB )
AT STEP
001 (1/4 LSB )
111
DIGITAL INPUT CODE
ANALOG OUTPUT VALUE
0
2
1
4
3
6
5
000 010 001 011 100 101
DIFFERENTIAL LINEARITY
ERROR (-1/4 LSB)
DIFFERENTIAL
LINEARITY ERROR (+1/4 LSB)
1 LSB
1 LSB
DIGITAL INPUT CODE
ANALOG OUTPUT VALUE
Figure 5a. Integral Nonlinearity Figure 5b. Differential Nonlinearity
0
2
1
3
000 010 001 011
ACTUAL
DIAGRAM
IDEAL DIAGRAM
ACTUAL
OFFSET
POINT
OFFSET ERROR
(+1 1/4 LSB)
IDEAL OFFSET
POINT
DIGITAL INPUT CODE
ANALOG OUTPUT VALUE
0
5
4
6
7
000 101 100 110 111
IDEAL DIAGRAM
GAIN ERROR
(-1 1/4 LSB)
IDEAL FULL-SCALE OUTPUT
ACTUAL
FULL-SCALE
OUTPUT
DIGITAL INPUT CODE
ANALOG OUTPUT VALUE
Figure 5c. Offset Error Figure 5d. Gain Error