What is an opamp that is suitable for designing a sensor?

In summary, the conversation discusses the need for a dual supply op-amp with low voltage drop, high input resistance (30-100MOhm), and low input offset voltage for designing a pH sensor. The speaker asks for advice on choosing an op-amp based on factors such as accuracy, operating conditions, power source, and desired lifetime. The suggested approach is to search for "electrometer op amp" or "ph meter opamp," with a specific recommendation being the OPA128 electrometer opamp from Texas Instruments. This op-amp has been successfully used in a project as an integrator with good overnight holding capabilities. It is recommended to follow the datasheet guidelines for board layout and input guarding.
  • #1
Minh Thanh
I am finding a dual supply op-amp which has rate of voltage dropping to be low , input resistance is high about 30 -100MOhm and input offset voltage is low. All of them serve me to design a sensor that is pH sensor. Can you give me some your ideas for choosing ? Thank you !
 
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  • #2
It is difficult to decide without considering several considerations.

What is the accuracy that you need? What conditions will this operate in? What is your power source? Is it a battery? What lifetime do you need?

BoB
 
  • #3
Search on ph meter opamp

my first hit:
http://www.linear.com/solutions/1191You need high Zin. Search on 'electrometer op amp".
I built an integrator with OPA128 electrometer opamp that'd hold a millivolt overnight with just an off the shelf polypropylene capacitor. You have to follow the datasheet directions for board layout and input guarding , though.

http://www.ti.com/lit/ds/symlink/opa128.pdf

old jim
 
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1. What is an opamp and how does it work?

An opamp, short for operational amplifier, is an electronic component that amplifies the difference between two input voltages. It has a high gain and is typically used in circuits to perform mathematical operations such as addition, subtraction, and integration. It consists of a differential amplifier and a feedback loop that helps to stabilize and control the output signal.

2. How is an opamp suitable for designing a sensor?

Opamps are suitable for designing sensors because they have high gain, low input impedance, and high output impedance. This allows them to accurately amplify small signals from sensors and minimize the loading effect on the sensor, ensuring the integrity of the measured signal. Opamps can also be configured in various ways to meet the specific requirements of different sensors.

3. What are the important characteristics to consider when choosing an opamp for sensor design?

When choosing an opamp for sensor design, some important characteristics to consider include gain, bandwidth, input and output impedance, offset voltage, noise, and power supply requirements. These factors will determine the accuracy, stability, and overall performance of the sensor circuit.

4. How do I select the appropriate opamp for my sensor design?

The best way to select the appropriate opamp for your sensor design is to first identify the specifications and requirements of your sensor circuit. This will help narrow down the options based on the opamp characteristics mentioned earlier. You can then compare different opamps from various manufacturers and choose the one that best fits your needs and budget.

5. Can I use any opamp for my sensor design?

No, not all opamps are suitable for sensor design. Some opamps may not have the required characteristics or may not be able to handle the specific requirements of your sensor circuit. It is important to carefully select an opamp that is specifically designed for sensor applications to ensure optimal performance and accuracy.

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