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Precision Data Converters Forum
Increasing the input impedance.
I previously posted a question about the input impedance of the THS4032 which is about 2M Ohms(http://e2e.ti.com/support/data_converters/precision_data_converters/f/73/t/194976.aspx). Is there a way I can increase it still further. Will it help if I use one of the isolation amplifiers from Texas Instruments?
What sort of signal/sensor are you looking at? If I recall correctly, you are feeding into an ADS8556, but you never did describe the signal you are trying to capture.
I am going to implement a PID controller for a scanning probe microscope on a C6713 DSK. The input signal will be either from a Photo Sensitive Diode (PSD) interface circuit or an amplitude demodulator. In both cases the input will be in the +-10V range. This will be provided to an ADS 8556 through the opamp on the EVM. At this point I do not have much information about the PSD interface circuit or the amplitude demodulator circuit, except that they are low power and probably provide current in the micro ampere range. I just want to increase the input impedance of the EVM as high as possible to minimize the possibility of drawing too much current from the input circuit and damaging it.
On the output side the C6713 is to be connected to a piezo amplifier through a DAC7741 EVM. I guess that the piezo amplifier should have high input impedance anyway so this side should be ok.
If there any more specifications that are required please let me know.
Is there any way I can i can increase the input impedance to Giga Ohms, say 100 G Ohms?
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