Gain and offset adjustment with voltage reference

gainoffsetoperational-amplifierprecisionvoltage-reference

I am building an instrument that relies on a precision sensor module. The sensor is factory-calibrated, and outputs 0-10Vdc. I believe the factory calibration to be better than anything I can attain, and thus do not want to create my own calibration curve for the sensor.

I want to read this output with a 16-bit ADC; however, most ADCs only accept 0-3Vdc input. I will likely need an offset/gain op amp circuit between the ADC and the sensor, but I want this to be referenced to a known voltage reference. For example, I also want to run a known precision voltage reference through the offset/gain circuit to known that a given reading from the ADC corresponds exactly to a given reading on the sensor independent of temperature and everything else that could affect the reading. I want to be sure that I can determine the exact voltage coming off the sensor.

Can someone provide a schematic for such a circuit? Or at least point me to such a resource.

Thank you,

Michael

EDIT:

A number of commenters have asked about the specifics of my application (sorry! it took me a bit to dig up the datasheet). I am interfacing with an INFICON Priani Capacitance Diaphragm Gauge (a vacuum sensor). The device has a signal output with an absolute maximum range of 0-10Vdc; however actual measurements stay within the 2.2-8.68Vdc range. The accuracy of the voltage output is not stated because the device operates on a logarithmic scale. Voltage is directly proportional to the logarithm of pressure. The data sheet states the pressure measurement (not voltage) is ±15% accurate at 50 mbar, ±5% at 1000 mbar, and ±2% accurate at atmospheric pressure. The conversion factor is P = 10^(U-5.5) where P is pressure in mbar, and U is voltage.

The logarithmic output of the sensor is why I am concerned about accuracy (not so much precision). Errors in voltage measurement are amplified exponentially by the logarithmic nature of the device.

Vacuum Gauge User Manual Inficon PCG410

Best Answer

Off course you always bump into a solution immediately after posting a question. Below is a TI Application Report explaining how to do exactly what I asked.

http://www.ti.com/lit/an/sloa097/sloa097.pdf

Hopefully, this question will at least be useful to others.

Sorry!

Michael