max5187beeg Maxim Integrated Products, Inc., max5187beeg Datasheet - Page 12

• Manufacturer Part Number: max5187beeg
• Description: 8-bit, 40mhz, Current/voltage-output Dacs
• Manufacturer: Maxim Integrated Products, Inc.

Gain error (Figure 5d) is the difference between the
ideal and the actual full-scale output voltage on the
transfer curve, after nullifying the offset error. This error
alters the slope of the transfer function and corre-
sponds to the same percentage error in each step.
Settling time is the amount of time required from the start
of a transition until the DAC output settles its new output
value to within the converter’s specified accuracy.
Digital feedthrough is the noise generated on a DAC’s
output when any digital input transitions. Proper board
layout and grounding will significantly reduce this
noise, but there will always be some feedthrough
caused by the DAC itself.
Total harmonic distortion (THD) is the ratio of the RMS
sum of the input signal’s first five harmonics to the fun-
damental itself. This is expressed as:
8-Bit, 40MHz, Current/Voltage-Output DACs
Figure 6. Differential to Single-Ended Conversion Using a Low-Distortion Amplifier
12
______________________________________________________________________________________
THD
**MAX5187 ONLY
*400Ω RESISTORS INTERNAL TO MAX5190 ONLY.
=
20
⋅
log
R
10µF






SET
D0–D7
+3V
+3V
**
V
0.1µF
2
Total Harmonic Distortion
2
+
0.1µF
V
3
CLK
2
REFO
REFR
Digital Feedthrough
AV
V
DGND
+
1
DD
V
4
2
10µF
MAX5187
MAX5190
+
Settling Time
REN
V
DV
5
Gain Error
DD
2






0.1µF
AGND
OUTP
OUTN
CREF
0.1µF
AV
DD
where V
V
harmonics.
Spurious-free dynamic range (SFDR) is the ratio of RMS
amplitude of the fundamental (maximum signal compo-
nent) to the RMS value of the next-largest distortion com-
ponent.
The MAX4108 low-distortion, high-input bandwidth
amplifier may be used to generate a voltage from the
array current output of the MAX5187. The differential
voltage across OUTP and OUTN is converted into a
single-ended voltage by designing an appropriate
operational amplifier configuration (Figure 6).
The low-distortion performance of two MAX5187/
MAX5190s supports analog reconstruction of in-phase
(I) and quadrature (Q) carrier components typically
used in quadrature amplitude modulation (QAM) archi-
tectures, where two separate buses carry the I and Q
data. A QAM signal is both amplitude and phase mod-
ulated, created by summing two independently modu-
lated carriers of identical frequency but different phase
(90° phase difference).
400Ω*
400Ω*
5
are the amplitudes of the 2nd- through 5th-order
I/Q Reconstruction in a QAM Application
Differential to Single-Ended Conversion
1
is the fundamental amplitude, and V
402Ω
402Ω
402Ω
Spurious-Free Dynamic Range
402Ω
-5V
+5V
MAX4108
OUTPUT
2
through