Operational amplifiers, or OpAmps, are versatile components in electronic circuits, pivotal for amplifying voltage signals. Their applications span across filtering, measuring, and analog computing, illustrating their integral role in signal processing. The non-inverting amplifier configuration of an OpAmp is particularly noteworthy for its ability to amplify an input voltage while maintaining the phase alignment with the input signal.

Gain Equation for a Non-Inverting Amplifier

The amplification, or gain, of a non-inverting amplifier, is crucial for understanding how the input signal is enhanced at the output. This gain (Av) is dependent on the feedback resistor (Rf) and the ground resistor (Rg), expressed through the equation:

In this exercise, employing a potentiometer to adjust Rf and Rg allows for dynamic control over the amplifier's gain, facilitating an exploration into the effects of varying resistance ratios.

Experimental Framework

Materials

• OP37 OpAmp, chosen for its availability in the ADALP2000 Analog Parts Kit and its resilience for experimental learning.
• Red Pitaya or equivalent, serving as both the signal generator and oscilloscope.
• Potentiometer, used in place of discrete resistors to enable adjustable gain.
• Ethernet cables, with a preference for CAT6, for connections due to their reliability and quality.

Setup

1. OpAmp Configuration: Follow the OP37 chip’s pinout to connect the power supply (+5V to U+ and -4V to U-), input, and output as per the non-inverting amplifier schematic, leaving non-essential pins disconnected.

2. Circuit Assembly: Utilize the potentiometer to achieve an adjustable resistance setup, enabling easy modulation of the amplifier's gain.

Procedure

1. Signal Application: Initiate a sine wave output from the Red Pitaya, connecting it to the amplifier's input.
2. Observation: With oscilloscope probes set to x10 mode at both the input and output, monitor the effects of adjusting the potentiometer on the amplifier’s output.
3. Analysis: Explore the boundaries of amplification, identifying the maximum gain before saturation occurs and examining the voltage levels at the inverting and non-inverting inputs, especially in saturation conditions.

Key Insights

• Amplification and Saturation: Determine the highest achievable amplification before saturation, noting the operational limits of the OpAmp.
• Voltage Comparison: Assess whether the inverting and non-inverting inputs maintain equivalent voltages under normal and saturation conditions.

Voltage Follower Consideration

A voltage follower, or unity gain buffer, is a specialized non-inverting amplifier setup where Rf=0 ohms and Rg is omitted (considered infinite), resulting in a gain of 1 (Av=1). This configuration is ideal for impedance matching, providing high input impedance and low output impedance without modifying the signal amplitude.

Conclusion

This comprehensive exercise not only demystifies the operation of non-inverting amplifiers but also highlights the practical aspects of adjusting gain through a potentiometer. By engaging with the setup, observation, and analysis of this circuit, learners gain a profound understanding of OpAmp functionalities and the pivotal role of resistance in shaping amplification, paving the way for advanced exploration into electronic circuit designs.