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AD8220 driving long cables/capacitances differential

Question asked by wildcard96 on May 14, 2014
Latest reply on May 22, 2014 by iamPhil

Hello everyone,

 

for my current design I plan to use the IA AD8220 (Gain: ~20dB, frequency: DC-10kHz) to readout a audio piezo transducer. The output signals has to be differential since it's connected to a high resolution diff-adc (24bits). Amplifier/Transducer and ADC are about 1000ft away from each other (twisted pair, awg28)! I expect a cable load capacitance in the range of 30-50nF.

 

Following single-ended to differential solutions came to my mind:

 

a) the ad8220 datasheet (p.24, figure 65) suggests the addition of one OP1177 to perform the conversion.

b) using an additional difference amp like the AD8273 in G=4 configuration (AN-1165, p.6) at the IA output

c) using a SSM2142 driver. this only is some sort of "last resort" due to the relativ high supply current (5mA), bulky cases and my experiences in other projects.

 

Thank you for your advices/other ideas.

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