Instrumentation Amplifier Design and Analysis
It is best to choose the Instrumentation amplifier. There are various differences between the instrumentation amplifier and isolation amplifier. An instrumentation amplifier is similar to an operational amplifier which is a closed loop device having a linear feedback. It is very important in electronic circuits as it has the constant gain factor. The gain error in the instrumentation amplifier is zero which is very useful.The input impedance of the instrumentation amplifier is infinite. It has zero noise level and offset dc is also zero. The output impedance of the instrumentation amplifier is also zero which is also the important characteristics of the instrumentation amplifier.
In practical consideration in electronic circuits, the output impedance, offset dc and noise level is very low.
Similarly, the input impedance of the instrumentation amplifier in practical consideration is very high. Also, the gain accuracy in this amplifier is high which is very useful in electronic circuits for various purposes.
Generally, there are 3 types of the instrumentation amplifier. They are termed as instrumentation amplifier using one operational amplifier, instrumentation amplifier using two operational amplifiers and instrumentation amplifier using three operational amplifiers.
Instrumentation Amplifier having 3 Operational Amplifiers
In various purposes, the important type of instrumentation amplifier used is an instrumentation amplifier using three operational amplifiers. This type of instrumentation amplifier is generally used because of its stages performance. It consists of two major stages. They are defined as the first stage and second stage.The first stage is also called the input stage. And, the second stage is called the differential stage. In the first stage i.e. in the input stage, the instrumentation amplifier offers very high input impedance. The reason for high input impedance is for achieving gain with a single resistor used. Also, this stage has two matched operational amplifiers.
Similarly, the second stage i.e. differential stage consists of a differential amplifier which has a high common mode rejection ratio. The instrumentation amplifier having three operational amplifiers is used in electronic circuits because it has high gain-bandwidth product having high common mode rejection ratio. Also, the gain in this type of instrumentation amplifier can be adjustable. It has a high gain.
Comparison of Instrumentation amplifier with Isolation and log amplifier
Isolation Amplifier- The isolation amplifier is also similar to the instrumentation amplifier but it has a fixed gain over various frequencies. The other important characteristics of isolation amplifier are that it has low output impedance and high input impedance.The isolation amplifier is used in various fields. For example, it is used in the biomedical instrument, the control system in the industry, electrical power plant, etc.
Hence, the isolation amplifier is very useful and it has various important purposes. The isolation amplifier can be achieved through two important methods. These two important methods are optically coupled and electromagnetically coupled.
Log Amplifier- Another important amplifier is a log amplifier which is used for compensating temperature. How many diodes and amplifiers are present in the log amplifier? It consists of two diodes and two operational amplifiers. In this type of amplifier, the current from the current source is passed through the diodes. By changing the values of various resistors, the compensation process is done.