CN0025

Precision, AC Reference Signal Attenuator Using the AD5546/AD5556 Multiplying DAC
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Circuit Function & Benefits

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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.



Figure 1: AC Signal Attenuation Configuration Using the AD5546/56 Precision DAC and the AD8610 Precision Op Amp (Simplified Schematic)

Circuit Description

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The AD5546/AD5556 are precision 16-/14-bit, multiplying, low power, current output, parallel input DACs. They operate from 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.

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.

Sample Products

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Samples

Product

Description

Available Product
Models to Sample

AD8610 Precision, Low Input Bias Current, Wide BW JFET Single Op Amp

AD8610ARMZ-R7

AD5556 Current-Output Parallel-Input, 14-Bit Digital-to-Analog Converter

AD5556CRUZ

AD5546 Current-Output Parallel-Input, 16-Bit Digital-to-Analog Converter

AD5546BRUZ

AD5546CRUZ