Practical Tips
When designing non-inverting amplifier circuits, component selection is crucial for optimal performance:
- LM358: General-purpose, low-cost. Good for single-supply designs but has crossover distortion.
- TL072: Low-noise JFET input. Excellent for audio, but needs dual supply for best performance.
- OPA2134: High-fidelity audio op-amp with very low distortion.
Resistor Selection: Keep values between 1kΩ and 100kΩ. Too low wastes power; too high introduces noise.
Why is the gain always ≥ 1?
The formula is A = 1 + (Rf/R1). Since resistors cannot be negative, the ratio is positive, so the total result must be at least 1. For attenuation (Gain < 1), use a voltage divider or inverting amplifier.
What is a Voltage Follower?
If you set Rf = 0 (short circuit) and remove R1 (open circuit), the Gain becomes 1. This "buffer" copies the input voltage but provides high current drive and high input impedance.
Can I use a single power supply (e.g., 5V and GND)?
Yes, but AC signals will clip at 0V (Ground). To amplify AC audio on a single supply, you must bias the input to half the supply voltage (Virtual Ground).
Why not just use a transistor?
Op-Amps are much easier to design with. Their gain is set precisely by two external resistors, independent of temperature or transistor variations (Beta).