Download CN-0025 利用AD5546/AD5556乘法DAC实现精密、交流基准信号衰减器

CIRCUIT FUNCTION AND BENEFITS
a single 2.7 V to 5.5 V supply with ±10 V multiplying references
for 4-quadrant outputs. Multiplying bandwidth is 4 MHz. Built
in 4-quadrant resistors facilitate resistance matching and
temperature tracking that minimize the number of components
needed for multiquadrant applications. Besides handling digital
waveforms decoded from parallel input data, the AD5546/
AD5556 handle low frequency ac reference signals for signal
attenuation, channel equalization, and waveform generation
applications.
This circuit provides precision, ac signal attenuation using the
AD5546/AD5556 DAC and the AD8610 precision operational
amplifier. This circuit provides accurate, low noise, high speed
output voltage capability and is well suited for process control,
automatic test equipment, and digital calibration applications.
CIRCUIT DESCRIPTION
The AD5546/AD5556 are precision 16-/14-bit, multiplying, low
power, current output, parallel input DACs. They operate from
+10V
VIN
–10V
R1
RCOM
R1
+5V
REF
R2
ROFS
ROFS
RFB
C8
2.2pF
+12V
C4
0.1µF
RFB
VDD
C2
0.1µF
IOUT
16/14-BIT
U1
AD5546/AD5556
–
C5
1µF
V+
U2
AD8610
GND
+
VOUT
V–
16/14 DATA
C6
0.1µF
WR LDAC RS
MSB
WR
LDAC
RS
MSB
C7
1µF
–12V
08344-001
C1
1µF
Figure 1. AC Signal Attenuation Configuration Using the AD5546/56 Precision DAC and the AD8610 Precision Op Amp (Simplified Schematic)
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An op amp is used in the current-to-voltage (I-V) stage of this
circuit. An op amp’s bias current and offset voltage are both
important selection criteria for use with precision current
output DACs. Therefore, this circuit employs the AD8610
op amp, which has ultralow offset voltage (100 µV maximum
for B grade) and bias current (10 pA maximum). The value of
C8 for this circuit is 2.2 pF, which is optimized to compensate
for the external output capacitance of the DAC.
LEARN MORE
ADIsimPower Design Tool. Analog Devices.
Kester, Walt. The Data Conversion Handbook. Chapters 3 and 7.
Analog Devices. 2005.
MT-015 Tutorial, Basic DAC Architectures II: Binary DACs.
Analog Devices.
MT-031 Tutorial, Grounding Data Converters and Solving the
Mystery of AGND and DGND. Analog Devices.
MT-101 Tutorial, Decoupling Techniques. Analog Devices.
Data Sheets
AD5546 Data Sheet.
AD5556 Data Sheet.
AD8610 Data Sheet.
REVISION HISTORY
6/09—Revision 0: Initial Version
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