A non-inverting amplifier is a type of electronic circuit used to amplify an input signal while maintaining its phase. It's called "non-inverting" because the output signal's polarity or phase is not inverted compared to the input signal. This means that when the input voltage increases, the output voltage also increases, and vice versa, in the same polarity.
The basic setup of a non-inverting amplifier consists of an operational amplifier (op-amp) and a few external components, mainly resistors. Here's how it operates:
Op-Amp Input Configuration: The op-amp has two input terminals – the inverting input (-) and the non-inverting input (+). In a non-inverting amplifier, the input signal is applied to the non-inverting input terminal (+).
Voltage Divider Feedback: A resistor (R1) is connected between the non-inverting input terminal (+) of the op-amp and the input signal source. Another resistor (R2) is connected between the non-inverting input terminal (+) and the op-amp's output.
Amplification Factor: The ratio of R2 to R1 determines the amplification factor of the circuit. The amplification factor, also known as the gain (A), is calculated using the formula: A = 1 + (R2 / R1). The gain can be adjusted by changing the values of these resistors.
Feedback Mechanism: The output of the op-amp is fed back to the non-inverting input terminal (+) through the voltage divider formed by R1 and R2. As the output voltage changes, it creates a feedback voltage at the non-inverting input that opposes any change in the input voltage. This feedback mechanism is what stabilizes the amplifier's operation and prevents saturation.
Amplified Output: When an input signal is applied to the non-inverting input, the op-amp amplifies it according to the gain formula. The amplified output signal appears across the output terminal of the op-amp.
Phase Preservation: Since the input is applied to the non-inverting input terminal, the output signal maintains the same phase as the input signal. This is in contrast to an inverting amplifier, where the input signal is applied to the inverting input, causing the output signal to be inverted in polarity.
In summary, a non-inverting amplifier amplifies an input signal while maintaining its phase. It is a widely used configuration in various electronic systems, such as audio amplifiers, signal conditioning circuits, and sensors. The gain of the amplifier can be adjusted by choosing appropriate resistor values, and the non-inverting configuration ensures that the output signal is in-phase with the input signal, making it useful for applications where phase preservation is important.