There could be several reasons why your non-inverting amplifier is not working as expected when the input voltage is a sine wave with an amplitude over 400mV and a frequency of 41.3kHz. Here are a few possibilities:
Saturation: The non-inverting amplifier has a limited output swing, determined by its power supply voltage and rail-to-rail specifications. If the amplified signal exceeds the maximum output voltage or goes too close to the supply rails, the amplifier can enter saturation. In this case, the output voltage will be clipped or distorted, leading to incorrect amplification. Check if your amplifier is operating within its specified output voltage range.
Bandwidth Limitations: Every operational amplifier has a finite bandwidth that determines the range of frequencies it can accurately amplify. If the input frequency is higher than the amplifier's bandwidth, the output signal may be distorted or attenuated. Ensure that your amplifier has sufficient bandwidth to handle the 41.3kHz input signal.
Input Impedance Mismatch: The non-inverting amplifier requires a high input impedance to prevent loading effects on the input signal. If the input impedance of the amplifier is too low or if there is a mismatch with the signal source, it can affect the amplifier's performance. Ensure that the input impedance of your amplifier is sufficiently high for your application.
Gain and Feedback Resistor Values: Check the values of the resistors used for setting the gain in your non-inverting amplifier configuration. If the gain is set too high, it may exceed the amplifier's capabilities and lead to instability or distortion. Verify that the gain and the feedback resistor values are appropriate for your desired amplification.
Power Supply Issues: Insufficient or noisy power supply can also impact the performance of an amplifier. Ensure that the power supply voltages are stable and meet the requirements specified by the amplifier's datasheet.
Component Degradation: Over time, components can degrade or fail, especially if they have been subjected to excessive heat, voltage, or current. Check for any damaged or worn-out components in your amplifier circuit.
It's important to analyze your circuit design, including the choice of components, layout, and specifications, to identify any potential issues that may be causing the non-inverting amplifier to malfunction. Additionally, double-check your connections and measurements to rule out any wiring errors.