A non-inverting amplifier is a type of electronic circuit commonly used in analog signal processing. Its primary function is to amplify an input signal while maintaining its original polarity. In other words, the output signal is a larger version of the input signal, and it's not inverted or flipped in phase.
Here's how a non-inverting amplifier works:
Basic Configuration: The core of a non-inverting amplifier consists of an operational amplifier (op-amp) and a few passive components like resistors. An op-amp is a high-gain differential amplifier that amplifies the voltage difference between its two input terminals.
Positive Feedback: In a non-inverting amplifier, the input signal is applied to the non-inverting (+) input terminal of the op-amp. This ensures that the input signal is in phase with the output. The inverting (-) input terminal of the op-amp is usually connected to a reference point, typically ground (0V).
Feedback Network: To establish the desired gain, a feedback network is created using resistors. A resistor (Rf) is connected between the output of the op-amp and the inverting input terminal. Another resistor (R1) is connected between the inverting input terminal and the signal source (Vin). This forms a voltage divider between the input signal and the feedback voltage, which helps determine the amplification factor.
Virtual Ground: Due to the high open-loop gain of op-amps, the voltage at the inverting input terminal is held virtually equal to the voltage at the non-inverting input terminal (which is the input voltage, Vin). This creates a virtual ground, which means that the inverting input is at a voltage very close to ground potential.
Gain Calculation: The gain (A) of the non-inverting amplifier is determined by the ratio of the feedback resistor (Rf) to the input resistor (R1), plus 1:
A = 1 + (Rf / R1)
Output Voltage: The output voltage (Vout) of the non-inverting amplifier is given by the product of the input voltage (Vin) and the gain (A):
Vout = A * Vin
Signal Amplification: As the input signal varies, the op-amp amplifies the voltage difference between the inverting and non-inverting inputs, resulting in an amplified output signal that is faithful to the input signal's shape and polarity.
It's important to note that while the non-inverting amplifier provides signal amplification, it has limitations imposed by the power supply voltage and the op-amp's characteristics. Exceeding these limits can result in distortion or clipping of the output signal.
In summary, a non-inverting amplifier is a circuit configuration that amplifies an input signal while maintaining its original polarity. It achieves this by using an operational amplifier, a feedback network of resistors, and a careful arrangement of connections to ensure that the input and output signals are in phase.