MOSFET Understanding Circuit Design
When designing circuits with MOSFETs, understanding the threshold voltage is crucial for proper functionality. This is the voltage required to turn the MOSFET on.
Many MOSFETs can operate effectively with a 12V power supply, as their threshold voltages typically range from 2V to 4V. This means the opamp needs to apply only approximately 4V to the gate.
Alternative Exploring BJT s
Consider substituting a Bipolar Junction Transistor (BJT), such as the 2N3904. Using a BJT might require careful selection of the resistor value, though a 100-ohm resistor often works.
Be aware that the current in the current sense resistor will be slightly higher than the collector current due to base current. However, this typically results in a minimal error, approximately 10% in worst-case scenarios.
“Understanding threshold voltage is key to efficient MOSFET circuit design.
Expert Analysis
Interactive Learning
Dive deeper with these interactive resources:
MOSFET Calculator
Calculate MOSFET operating parameters and optimize your design.
BJT vs. MOSFET Comparison
A side-by-side comparison to understand pros and cons.
Resistor Considerations
The resistor is essential for damping potential oscillations that may arise due to capacitive loads. It helps to stabilize the circuit. This is particularly relevant when using MOSFETs.
However, the resistor isn't strictly necessary when employing a BJT in the circuit.