Circuit Design and Analysis of an instrumentation amplifier with Electronic Gain Control is discussed in this example. This circuit is implemented with five operational amplifiers and two N-channel MOS Transistors also known as nMOS to realize linear electronic gain control for applications where Automatic Gain Control (AGC) requires electronic gain adjustment. For more examples see • Electrical Engineering... . The electronic gain control function can also be realized using JFET Transistors instead of MOSFET transistors. The input voltages in this precision amplifier can be the tiny voltage across an optical or thermal sensor that can't provide current. The instrumentation amplifier receives the input voltage and amplifies it to a reasonable level so that the drain of MOSFET is kept at low voltage to enforce MOSFET transistor in deep ohmic region of I-V curve. This is required so that FET transistor is effectively working as a voltage controlled resistor. The Circuit is analyzed and overall gain is computed using a combination of op amp virtual short, Kirchhoff's circuit laws including KCL and KVL and properties of FET transistor in deep linear region. Potential choices of op amps for instance from Texas instrument and Transistor from for instance TI or Nexperia are also discussed.
30 сен 2024
