Questions concerning the THS4524EVM.
1). Max Gain: What is the maximum recommended gain for the THS4524EVM?
2). Noise Level: The referred to input (RTI) amplifier noise level is usually much larger with low gain, compared with high gain. But the noise specs for the THS4524EVM do not give any dependence on gain. What is the noise spec, or at least an estimated noise level, for X1 gain versus X10 gain versus X100 gain?
3). Power Supply: What is the down side to choosing a single polarity power source, instead of a dual polarity power source?
4). Amplifier Input: We will be using this amplifier in a low-frequency (100Hz to 10kHz) application (similar to Figure 84 in the THS4524 data sheet). The sensor feeding the amplifier will be a magnetic-field sensing coil. The input resistance to the amplifier will be 15 Ohms from ground to the + input and 15 Ohms from ground to the - input. Are there any other recommended changes to Figure 84 in the THS4524 data sheet for this type of application?
5). Amplifier Output: We need to drive a 15 meter long twisted-pair shielded cable (about 15 pF/ft X 15m X 3.28ft/m = 738 pF). Will there be any problems with the THS4524 driving this length of cable? The data sheet indicates that we should put small resistors in series with the output when driving a capacitive load. Figure 66 in the THS4524 data sheet gives the recommended resistor for various capacitance values and for a 1000 Ohm load. What value output resistors should be used when the load at the other end of the cable is a high-impedance amplifier (e.g. greater than 10 MOhms)?
Thank you for your help.
Ben Sternberg
University of Arizona
bkslasi@email.arizona.edu